Radeon 7500 10 bit DAC support

I've updated 10-bit DAC support for the 7500 in my files and in David
Brainard's beta script updates for 10-bit DAC support in
Psychtoolbox. The files are at
<http://www.cvs.rochester.edu/people/b_singer/Radeon10BitGamma/>.

The new G4's have as a base model one that includes the dual-head
Radeon 7500, and we just got one here at CVS I can test on. For $1600
you have a 800MHz G4 with 2 screens, one of which is analog VGA which
supports 10-bit gamma tables in the drivers out of the box! Of course
out of the box it runs MacOS X, and 10-bit support doesn't seem to be
enabled via Classic mode, according to one report. I haven't tried it.

Have fun!

Ben