Improved asset system.
Refactored Game and Window:
Window is now integrated into Game.
System is split into rendering and updating thread, also 2 threads for deferring routines.
Game is now able to update physics in the update thread while the game is rendering (TBD).
CoRoutines need to be implemented.
Improved deferred routines. Added OpenGL deferred routine instead of OpenGLTick. Deferred Asset loading, fixed loading for Texture2D and Model.
Some improvements on asset loading.