Import global functions and constants for enhanced performance

This is better for performance because these then don't need to be reevaluated every time they are called.

When encountering an unqualified function or constant reference, PHP will first try to locate a symbol in the current namespace by that name, and then fall back to the global namespace.
This short-circuits the check, which has substantial performance effects in some cases - in particular, ord(), chr() and strlen() show ~1500x faster calls when they are fully qualified.

However, this doesn't mean that PM is getting a massive amount faster. In real world terms, this translates to about 10-15% performance improvement.
But before anyone gets excited, you should know that the CodeOptimizer in the PreProcessor repo has been applying fully-qualified symbol optimizations to Jenkins builds for years, which is one of the reasons why Jenkins builds have better performance than home-built or source installations.
We're choosing to do this for the sake of future SafePHP integration and also to be able to get rid of the buggy CodeOptimizer, so that phar and source are more consistent.

src/pocketmine/block/BaseRail.php

@@ -26,6 +26,13 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function array_map;
+use function array_reverse;
+use function array_search;
+use function array_shift;
+use function count;
+use function implode;
+use function in_array;
 
 abstract class BaseRail extends Flowable{
 
@@ -98,7 +105,7 @@ abstract class BaseRail extends Flowable{
 			$meta = array_search(array_reverse($connections), $lookup, true);
 		}
 		if($meta === false){
-			throw new \InvalidArgumentException("No meta value matches connections " . implode(", ", array_map('dechex', $connections)));
+			throw new \InvalidArgumentException("No meta value matches connections " . implode(", ", array_map('\dechex', $connections)));
 		}
 
 		return $meta;

src/pocketmine/block/Beetroot.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Beetroot extends Crops{
 

src/pocketmine/block/Block.php

@@ -38,6 +38,8 @@ use pocketmine\metadata\Metadatable;
 use pocketmine\metadata\MetadataValue;
 use pocketmine\Player;
 use pocketmine\plugin\Plugin;
+use function array_merge;
+use const PHP_INT_MAX;
 
 class Block extends Position implements BlockIds, Metadatable{
 

src/pocketmine/block/BlockFactory.php

@@ -25,6 +25,10 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\level\Position;
+use function file_get_contents;
+use function json_decode;
+use function max;
+use function min;
 
 /**
  * Manages block registration and instance creation

src/pocketmine/block/BrownMushroomBlock.php

@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\block;
 
 use pocketmine\item\Item;
+use function mt_rand;
 
 class BrownMushroomBlock extends RedMushroomBlock{
 

src/pocketmine/block/Carrot.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Carrot extends Crops{
 

src/pocketmine/block/CoalOre.php

@@ -26,6 +26,7 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\item\TieredTool;
+use function mt_rand;
 
 class CoalOre extends Solid{
 

src/pocketmine/block/Crops.php

@@ -27,6 +27,7 @@ use pocketmine\event\block\BlockGrowEvent;
 use pocketmine\item\Item;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 abstract class Crops extends Flowable{
 

src/pocketmine/block/DeadBush.php

@@ -27,6 +27,7 @@ use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 class DeadBush extends Flowable{
 

src/pocketmine/block/DiamondOre.php

@@ -26,6 +26,7 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\item\TieredTool;
+use function mt_rand;
 
 class DiamondOre extends Solid{
 

src/pocketmine/block/DoublePlant.php

@@ -27,6 +27,7 @@ use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 class DoublePlant extends Flowable{
 	public const BITFLAG_TOP = 0x08;

src/pocketmine/block/EmeraldOre.php

@@ -26,6 +26,7 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\item\TieredTool;
+use function mt_rand;
 
 class EmeraldOre extends Solid{
 

src/pocketmine/block/Fire.php

@@ -31,6 +31,8 @@ use pocketmine\event\entity\EntityDamageByBlockEvent;
 use pocketmine\event\entity\EntityDamageEvent;
 use pocketmine\item\Item;
 use pocketmine\math\Vector3;
+use function min;
+use function mt_rand;
 
 class Fire extends Flowable{
 

src/pocketmine/block/Glowstone.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Glowstone extends Transparent{
 

src/pocketmine/block/Grass.php

@@ -32,6 +32,7 @@ use pocketmine\level\generator\object\TallGrass as TallGrassObject;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
 use pocketmine\utils\Random;
+use function mt_rand;
 
 class Grass extends Solid{
 

src/pocketmine/block/Gravel.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Gravel extends Fallable{
 

src/pocketmine/block/ItemFrame.php

@@ -28,6 +28,7 @@ use pocketmine\math\Vector3;
 use pocketmine\Player;
 use pocketmine\tile\ItemFrame as TileItemFrame;
 use pocketmine\tile\Tile;
+use function lcg_value;
 
 class ItemFrame extends Flowable{
 	protected $id = Block::ITEM_FRAME_BLOCK;

src/pocketmine/block/LapisOre.php

@@ -26,6 +26,7 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\item\TieredTool;
+use function mt_rand;
 
 class LapisOre extends Solid{
 

src/pocketmine/block/Leaves.php

@@ -28,6 +28,7 @@ use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 class Leaves extends Transparent{
 	public const OAK = 0;

src/pocketmine/block/Liquid.php

@@ -31,6 +31,9 @@ use pocketmine\level\Level;
 use pocketmine\level\sound\FizzSound;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Vector3;
+use function array_fill;
+use function lcg_value;
+use function min;
 
 abstract class Liquid extends Transparent{
 

src/pocketmine/block/Melon.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Melon extends Transparent{
 

src/pocketmine/block/MelonStem.php

@@ -27,6 +27,7 @@ use pocketmine\event\block\BlockGrowEvent;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
+use function mt_rand;
 
 class MelonStem extends Crops{
 

src/pocketmine/block/MonsterSpawner.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\TieredTool;
+use function mt_rand;
 
 class MonsterSpawner extends Transparent{
 

src/pocketmine/block/Mycelium.php

@@ -27,6 +27,7 @@ use pocketmine\event\block\BlockSpreadEvent;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
+use function mt_rand;
 
 class Mycelium extends Solid{
 

src/pocketmine/block/NetherQuartzOre.php

@@ -26,6 +26,7 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\item\TieredTool;
+use function mt_rand;
 
 class NetherQuartzOre extends Solid{
 

src/pocketmine/block/NetherWartPlant.php

@@ -29,6 +29,7 @@ use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 class NetherWartPlant extends Flowable{
 	protected $id = Block::NETHER_WART_PLANT;

src/pocketmine/block/Potato.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Potato extends Crops{
 

src/pocketmine/block/PumpkinStem.php

@@ -27,6 +27,7 @@ use pocketmine\event\block\BlockGrowEvent;
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
+use function mt_rand;
 
 class PumpkinStem extends Crops{
 

src/pocketmine/block/RedMushroomBlock.php

@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\block;
 
 use pocketmine\item\Item;
+use function mt_rand;
 
 class RedMushroomBlock extends Solid{
 

src/pocketmine/block/RedstoneOre.php

@@ -28,6 +28,7 @@ use pocketmine\item\ItemFactory;
 use pocketmine\item\TieredTool;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 class RedstoneOre extends Solid{
 

src/pocketmine/block/Sapling.php

@@ -28,6 +28,7 @@ use pocketmine\level\generator\object\Tree;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
 use pocketmine\utils\Random;
+use function mt_rand;
 
 class Sapling extends Flowable{
 	public const OAK = 0;

src/pocketmine/block/SignPost.php

@@ -29,6 +29,7 @@ use pocketmine\math\Vector3;
 use pocketmine\Player;
 use pocketmine\tile\Sign as TileSign;
 use pocketmine\tile\Tile;
+use function floor;
 
 class SignPost extends Transparent{
 

src/pocketmine/block/StandingBanner.php

@@ -30,6 +30,7 @@ use pocketmine\math\Vector3;
 use pocketmine\Player;
 use pocketmine\tile\Banner as TileBanner;
 use pocketmine\tile\Tile;
+use function floor;
 
 class StandingBanner extends Transparent{
 

src/pocketmine/block/TNT.php

@@ -30,6 +30,9 @@ use pocketmine\item\Item;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
 use pocketmine\utils\Random;
+use function cos;
+use function sin;
+use const M_PI;
 
 class TNT extends Solid{
 

src/pocketmine/block/TallGrass.php

@@ -27,6 +27,7 @@ use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function mt_rand;
 
 class TallGrass extends Flowable{
 

src/pocketmine/block/Vine.php

@@ -28,6 +28,8 @@ use pocketmine\item\Item;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Vector3;
 use pocketmine\Player;
+use function max;
+use function min;
 
 class Vine extends Flowable{
 	public const FLAG_SOUTH = 0x01;

src/pocketmine/block/Wheat.php

@@ -25,6 +25,7 @@ namespace pocketmine\block;
 
 use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
+use function mt_rand;
 
 class Wheat extends Crops{