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/BossMob.h

@@ -14,7 +14,7 @@ public:
 	BossMob(Level *level);
 
 	virtual int getMaxHealth();
-	virtual bool hurt(shared_ptr<BossMobPart> bossMobPart, DamageSource *source, int damage);
+	virtual bool hurt(std::shared_ptr<BossMobPart> bossMobPart, DamageSource *source, int damage);
 	virtual bool hurt(DamageSource *source, int damage);
 
 protected: