[Cairo] Rectangle-based clipping for surfaces

[Carl Worth]

On Oct 20, Keith Packard wrote:
 > Around 16 o'clock on Oct 20, Carl Worth wrote:
 > > Instead, if we restrict the new API to the Xlib-specific backend then
 > > it can just use the existing Xlib Region object:
 > 
 > Should we use the libpixregion datatype instead?

Yes, we probably should. But before we start exposing that through
the Cairo interface, I'd like to get it merged with the code in libic
and get the whole mess renamed something sensible, (and made to match
the style of the Cairo interface).

The only proposal I've heard for a new name so far is libpixmap. With
that name the two primary datatypes in the library could be:

	pm_image_t
and	pm_region_t

Unless someone has a better idea. (One minor issue I have is that pm
suggests "power management" to me as in APM).

-Carl