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/QuartzBlockTile.h

@@ -39,7 +39,7 @@ public:
 	int getSpawnResourcesAuxValue(int data);
 
 protected:
-	shared_ptr<ItemInstance> getSilkTouchItemInstance(int data);
+	std::shared_ptr<ItemInstance> getSilkTouchItemInstance(int data);
 
 public:
 	int getRenderShape();