[depends] Add giflib.
[gif] - Add proper gif implementation.
[TextureManager] Use new gif implementation and remove now unused AnimatedGif class
[GUITexture] Change animation code.
[*RFC*][GUITexture] Add m_animated to CTextureInfo and set it when filename is set.
[application] - small refactor for user splash handling (allow Splash.gif)
[Splash/GUIImage/GUITexture] - make the splash aware of animations
[application] - render the splash during render() and process it in framemove if it is animated - do this until the animation was finished at least once to the end