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/EntityPos.cpp

@@ -34,7 +34,7 @@ EntityPos::EntityPos(float yRot, float xRot)
 	move = false;
 }
 
-EntityPos *EntityPos::lerp(shared_ptr<Entity> e, float f)
+EntityPos *EntityPos::lerp(std::shared_ptr<Entity> e, float f)
 {
 	double xd = e->x+(x-e->x)*f;
 	double yd = e->y+(y-e->y)*f;