[IDEA] shrink xrender featureset

[Maarten Maathuis]

Currently there exist several operations in xrender that are better
off client side or through some other graphic api (imo). Think of
trapezoid rasterisation, gradient rendering, etc. Doing this stuff
client side avoids unforseen migration issues and doesn't create any
false impressions with the api users.

My suggestion would be to deprecate everything, except solid,
composite, cursor stuff and glyphs. The idea is to stop doing
seemingly arbitrary graphics operations that end up causing slowness
most of the time (if not worked around "properly"). At this stage
noone accelerates these operations, so there can be no complaints
about that.

xrender is here to stay, but there are limits to it, so let's accept
this and move on (for other needs).

How do others feel about this?

Maarten.