shared_ptr -> std::shared_ptr

This is one of the first commits in a plan to remove all `using namespace std;` lines in the entire codebase as it is considered anti-pattern today.

Minecraft.World/CactusTile.h

@@ -30,10 +30,10 @@ public:
 	virtual bool mayPlace(Level *level, int x, int y, int z);
 	virtual void neighborChanged(Level *level, int x, int y, int z, int type);
 	virtual bool canSurvive(Level *level, int x, int y, int z);
-	virtual void entityInside(Level *level, int x, int y, int z, shared_ptr<Entity> entity);
+	virtual void entityInside(Level *level, int x, int y, int z, std::shared_ptr<Entity> entity);
 	//@Override
     void registerIcons(IconRegister *iconRegister);
-	
+
 	// 4J Added so we can check before we try to add a tile to the tick list if it's actually going to do seomthing
 	virtual bool shouldTileTick(Level *level, int x,int y,int z);
 };