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.Client/SlimeModel.cpp

@@ -27,9 +27,9 @@ SlimeModel::SlimeModel(int vOffs)
     }
 	else
 	{
-		eye0 = nullptr;
-		eye1 = nullptr;
-		mouth = nullptr;
+		eye0 = NULL;
+		eye1 = NULL;
+		mouth = NULL;
 	}
 	cube->compile(1.0f/16.0f);
 }
@@ -39,7 +39,7 @@ void SlimeModel::render(shared_ptr<Entity> entity, float time, float r, float bo
     setupAnim(time, r, bob, yRot, xRot, scale, entity);
 
     cube->render(scale,usecompiled);
-    if (eye0!=nullptr)
+    if (eye0!=NULL)
 	{
         eye0->render(scale,usecompiled);
         eye1->render(scale,usecompiled);