Changed signitures of Several BLockHandler Methods

Changed the signitures of the following to use interfaces:
GetPlacementBlockTypeMeta
OnPlaced
OnPlacedByPlayer
OnDestroyed
OnNeighbourChanged
NeighbourChanged
OnUse
CanBeAt
Check

src/Blocks/WorldInterface.h

@@ -22,4 +22,6 @@ public:
 	/** Spawns item pickups for each item in the list. May compress pickups if too many entities. All pickups get the speed specified: */
 	virtual void SpawnItemPickups(const cItems & a_Pickups, double a_BlockX, double a_BlockY, double a_BlockZ, double a_SpeedX, double a_SpeedY, double a_SpeedZ, bool IsPlayerCreated = false) = 0;
 	
+	/** Spawns a mob of the specified type. Returns the mob's EntityID if recognized and spawned, <0 otherwise */
+	virtual int SpawnMob(double a_PosX, double a_PosY, double a_PosZ, cMonster::eType a_MonsterType) = 0;
 };