Added algorithm prose for process_pyramids_barrier()
The prose is RFC, its code is TBD. Done pyramids_barrier()
wrapper.  Dropped references to InkcutPath code.
Window of test_drive.py increased to 800x600. Much nicer.
Added examples directory to Makefile. Renamed pyramid to 'pyramids';
but alas, the algorithm prose only uses slanted barriers to implement the
illusion of pyramids.