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/HashExtension.h

@@ -7,10 +7,10 @@ namespace std
 	{
 
 		template<class T>
-		class hash< shared_ptr<T> >
+		class hash< std::shared_ptr<T> >
 		{
 		public:
-			size_t operator()(const shared_ptr<T>& key) const
+			size_t operator()(const std::shared_ptr<T>& key) const
 			{
 				return (size_t)key.get();
 			}