ggiart-0.2pre1

[soyt]

A new ggiart release is available at
http://soyt.free.fr/get/ggiart-0.2pre1.tar.gz

Lots of code cleanup. I also added rgb and rgba buffer affine function.

However I have difficulties with cross visual rendering. It should
work but I get weird things when reading alpha channel back from a
visual. I'll try to solve this for 0.2 release.