Announce: Xlib-style drawing on RGB buffer

[Havoc Pennington <rhp zirx pair com>]

Hi,

People playing with the canvas, or just GdkRGB or any other kind of image
buffer, may miss convenient Xlib-style drawing functions. These are a bit
faster than libart's vector paths, at the expense of quality.

I noticed in a recent announce for GNU plotutils that they had extracted
these from X to use for rendering bitmap files. So I in turn extracted
them from plotutils. I've cleaned things up a bit - killed some namespace
pollution, killed gratuitous compatibility with pre-ANSI compilers, added
some const. However I didn't touch the meaningful code. You can find the
result in CVS under guppi2/src/aux/.

I remember someone(s) asking about something like this, so I thought I'd
announce it. If other people would find the library useful we could break
it out of Guppi.

Havoc