Surface creation now specifies the exact format, not only the bit depth
of each surface which is used for rendering.
Additionally we now actually store the surfaces in that format, instead
of converting everything to 32bpp when drawing or e.g. handling palettes.
The new command return dirty area to be used
by users that want spice to render localy or
into some framebuffer (sdl / vnc)
Signed-off-by: Izik Eidus <ieidus@redhat.com>