1. -Add play animation logic.
1. -Add building png.
2. -Restore camera fov in EditCameraWnd.
1. -Don't make some Matrix operation function const, because we may change the behavior in derived class.
Merge branch 'master' of https://github.com/beyondlwm/FCEngine
1. -Refactor camera. use invalidate flag to avoid unnecessary calculation.
2. -Add StarRaidersCenter
3. -Add HUDButton
4. -Add GameConfig.bcf
5. -Add IsVisible virtual function for window.