Revert "Project modernization (#630)"

This code was not tested and breaks in Release builds, reverting to restore
functionality of the nightly. All in-game menus do not work and generating
a world crashes.

This reverts commit a9be52c41a.

Minecraft.World/Mob.h

@@ -27,7 +27,7 @@ class Mob : public LivingEntity
 public:
 	// 4J-PB - added to replace (e instanceof Type), avoiding dynamic casts
 	eINSTANCEOF GetType()						{ return eTYPE_MOB;}
-	static Entity *create(Level *level) { return nullptr; }
+	static Entity *create(Level *level) { return NULL; }
 
 public:
 	static const float MAX_WEARING_ARMOR_CHANCE;