rc5 -- pyp_networking bugfix and new debugging option

Added the parameter debugLoad to the loadPedigree() function in pyp_newclasses.py. It defaults to False; when True it loads the pedigree without using a try-except block so that errors are not suppressed.

Fixed pyp_network/mean_geodesic() to properly catch an exception raised by NetworkX when no path exists between two nodes in a graph.