Add proper gif implementation.
[TextureManager] Use new gif implementation.
[win32] Remove now unused AnimatedGif class.
[GUITexture] Change animation code.
[*RFC*][GUITexture] Add m_animated to CTextureInfo and set it when filename is set.
[Gif] Restrict the memory consumption to 82944000 bytes (about 79 MB), which is equivalent to 10 full hd frames.