GFC and GTEC2Dlib cores are similar - which facilitates porting programs
between the two libraries. GFC contains extended functionality for 
maths and physics programming. 
The list below shows the major features of GTEC2Dlib 
that are missing in GFC.

GTec classes not implemented in GFC:
 - CSound: a different implementation of sounds
 - CTexture: bitmap files can be loaded to CGraphics objects
 - CSpriteTriangle, CSpritePoint
 - CSpriteList
 - CHealthBar

CGameApp - functions not implemented:
 - InitializeGL
 - InitializeAudio

CGame - functions not implemented:
 - SetSize
 - SetGameTime
 - ResetGameTime
 - IsExit
 - SetGameMode
 - ResumeGame (implemented by PauseGame)
 - ExitGame
 - DispatchEvents (implemented as OnEvent)

CSprite - functions not implemented:
 - Move(double) - only version with a vector or two numbers is available
 - ResetTime
 - animation function - GFC implementation is different
 - GetVelocity / SetVelocity - named GetSpeed / SetSpeed in GFC 
 - MarkForRemoval / IsMarked replaced by Delete / deleted
 - SetColor / SetAlpha/ SetFilled / SetTexture

CColor - functions not implemented:
 - None
 - SetAlpha




