Beta 20 -- Major bugfixes for LightAnimal handling

03/22/2007 Minor documentation fixes and additions.

03/22/2007 Added a new method, savegraph(), to
pyp_newclasses/NewPedigree for saving graphs to
adjacency matrices.

03/22/2007 Added a new value of pedsource,
'graphfile', which can load a pedigree stored as
a directed graph in a text file in an adjacency
list.

03/22/2007 Added a new argument to
pyp_utils/renumber(), animaltype, that allows for
proper handling of NewAnimal versus LightAnimal
instances.

03/22/2007 Fixed a bug in
pyp_newclasses/NewPedigree::preprocess() that
prevented correct loading of pedigrees using the
LightAnimal class. No namemap or namebackmap can
be formed using LightAnimal objects because they
have no name property. Also made related changes
in pyp_db, pyp_nrm, and pyp_utils, most notably to
pyp_utils/renumber().