Modify framebuffer and NGA framebuffer to read screen size from board model dtb file. Optimise memory usuage of frame buffer Add example minigui application with hooks to profiler (which writes results to S:\). Modified NGA framebuffer to run its own dfc queue at high priority

The icons for use on MacOS X were created by Jacob Rus <jrus@fas.harvard.edu>
with some feedback from the folks on pythonmac-sig@python.org.