WIP, multithreaded loading based on exceptions, very slow probably.

src/Game/Game.cpp

@@ -4,6 +4,7 @@
 
 Game::Game(int argc, char* argv[])
 {
+    ResourceManager::AssertIsMainThread();
     ResourceManager::RegisterType<ConfigFile>("ConfigFile");
     ResourceManager::RegisterType<Model>("Model");
     ResourceManager::RegisterType<Texture>("Texture");