Added Matrix4::GetDeterminantAffine
Completed Vector3 vectors
Fixed Drawable destructor
Added some comments
Added backgrounds
Fixed pixel flipping (ex:horizontal was vertical)
Slightly changed scene background behavior
Added Texture backgrounds
Fixed RenderTexture
Added 16bits demo
Reworked ResourceLoader
Added (move) assignement operator to Model
Optimized some format conversions

Thanks to kristofjé
Fixed ResourceRef not removing references
Fixed material texture loader leaks

Also made it exception-safe
Added ModelLoader

Changed Model::SetMesh behavior
Changed Resource::SetPersistent default argument
Added Scene::GetActiveCamera()

Also fixed a warning when instancing is used without lighting
Fixed last commit
Added String::Append(str, length);