Blender Git Loki

Added ability to render Zbuffer to an image.
Just use SHIFT-F3 and save an image.

Basically all this does is copy the zbuffer to a new Image buffer
and pass that to the save image function.

Sample output:
http://www.cs.umn.edu/~mein/blender/kungfu_zbuf255.jpg

Also thanks to Jesterking for helping me debug dumbness... ;)
and the nice screenshot.

Kent