Tool: cleanup durability handling, closes #379

long overdue... this isn't quite as extensible as the original api3/blocks system was, but this is primarily intended to replace Item->useOn(). If plugins want to use it it can be extended later on.

src/pocketmine/item/Pickaxe.php

@@ -23,7 +23,9 @@ declare(strict_types=1);
 
 namespace pocketmine\item;
 
+use pocketmine\block\Block;
 use pocketmine\block\BlockToolType;
+use pocketmine\entity\Entity;
 
 class Pickaxe extends TieredTool{
 
@@ -42,4 +44,15 @@ class Pickaxe extends TieredTool{
 	public function getAttackPoints() : int{
 		return self::getBaseDamageFromTier($this->tier) - 2;
 	}
+
+	public function onDestroyBlock(Block $block) : bool{
+		if($block->getHardness() > 0){
+			return $this->applyDamage(1);
+		}
+		return false;
+	}
+
+	public function onAttackEntity(Entity $victim) : bool{
+		return $this->applyDamage(2);
+	}
 }