wraster replacement in libs-back

[DTW-Thalion]

@fredkiefer,

I took an hour and went through wraster with a view of how to remove it and replace it.

On the server side, it is trivial to do - 90% of the wraster code is unused, and can be deleted. The parts that are used in Xlib are RContext, RXImage, and RGetClosestXColor/RGBtoPixel. 6 call touchpoints. On the consumer side, there are about 39 call touchpoints.

Cairo is the default and art doesn't use wraster at all - which is good as the fallback.

So my thought is you could move the x11 server to plain Xlib, then you could decide whether to retire the Xlib graphics backend (cleanest path), or we rewrite its 39 call sites to plain Xlib.

Thoughts?

[fredkiefer]

You make this change sound so easy :-)
What we are not very good at GNUstep is in retiring old functionality. That is why we still have the xdps backend and why we still keep lib and art. If these are useful for somebody out there, we keep them even if some minimal maintenance is required from time to time.

If there is a way to move all the usages of the wraster code strictly into the xlib backend this would be the preferred approach. That way we won't get rid of waster, but its usage will be localized to an obsolete backend.