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/MenuBackup.h

@@ -7,11 +7,11 @@ class MenuBackup
 {
 private:
 	unordered_map<short, ItemInstanceArray *> *backups;
-	shared_ptr<Inventory> inventory;
+	std::shared_ptr<Inventory> inventory;
 	AbstractContainerMenu *menu;
 
 public:
-	MenuBackup(shared_ptr<Inventory> inventory, AbstractContainerMenu *menu);
+	MenuBackup(std::shared_ptr<Inventory> inventory, AbstractContainerMenu *menu);
 
 	void save(short changeUid);