Added a way to get a framebuffer interface for a window, and also a way to create a software renderer for an arbitrary surface. The software renderer has been re-routed to use the framebuffer interface, which makes it possible to have software rendering available even on simple ports.

#!/bin/sh
#
# Print the current source revision, if available

# FIXME: this prints the tip, which isn't useful if you're on a different
#  branch, or just not sync'd to the tip.
hg tip --template 'hg-{rev}:{node|short}' || (echo "hg-0:baadf00d"; exit 1)