Fix some errors with meshrenderer moving to engine that gemini didnt have time to fix

Will have to resync how to load more meshes. Probably need a command to do it but for now not needed.

Juliet/include/Engine/Engine.h

@@ -15,7 +15,7 @@ namespace Juliet
     void InitializeEngine(JulietInit_Flags flags);
     void ShutdownEngine();
 
-    void LoadApplication(IApplication& app, Arena* arena);
+    void LoadApplication(IApplication& app);
     void UnloadApplication();
 
     void RunEngine();