BinaryStream no longer extends stdClass, fixed a couple of minor bugs

Seems :shoghi: used stdClass to silence IDEs, which before ALPHA5 would complain about myriad undefined fields due to lack of type checking (switch based on packet id 🤦)

src/pocketmine/Player.php

@@ -1875,7 +1875,7 @@ class Player extends Human implements CommandSender, InventoryHolder, ChunkLoade
 		$pk->spawnX = $spawnPosition->getFloorX();
 		$pk->spawnY = $spawnPosition->getFloorY();
 		$pk->spawnZ = $spawnPosition->getFloorZ();
-		$pk->hasBeenLoadedInCreative = 1;
+		$pk->hasAchievementsDisabled = 1;
 		$pk->dayCycleStopTime = -1; //TODO: implement this properly
 		$pk->eduMode = 0;
 		$pk->rainLevel = 0; //TODO: implement these properly

src/pocketmine/level/particle/FloatingTextParticle.php

@@ -87,8 +87,6 @@ class FloatingTextParticle extends Particle{
 			$pk->speedZ = 0;
 			$pk->yaw = 0;
 			$pk->pitch = 0;
-			$pk->item = 0;
-			$pk->meta = 0;
 			$flags = 0;
 			$flags |= 1 << Entity::DATA_FLAG_INVISIBLE;
 			$flags |= 1 << Entity::DATA_FLAG_CAN_SHOW_NAMETAG;

src/pocketmine/network/mcpe/protocol/MobArmorEquipmentPacket.php

@@ -24,6 +24,7 @@ namespace pocketmine\network\mcpe\protocol;
 #include <rules/DataPacket.h>
 
 
+use pocketmine\item\Item;
 use pocketmine\network\mcpe\NetworkSession;
 
 class MobArmorEquipmentPacket extends DataPacket{

src/pocketmine/network/mcpe/protocol/UseItemPacket.php

@@ -24,6 +24,7 @@ namespace pocketmine\network\mcpe\protocol;
 #include <rules/DataPacket.h>
 
 
+use pocketmine\item\Item;
 use pocketmine\network\mcpe\NetworkSession;
 
 class UseItemPacket extends DataPacket{

src/pocketmine/utils/BinaryStream.php

@@ -25,7 +25,7 @@ namespace pocketmine\utils;
 
 use pocketmine\item\Item;
 
-class BinaryStream extends \stdClass{
+class BinaryStream{
 
 	public $offset;
 	public $buffer;