Implement the bzr documentation/information autogeneration plan: * Add new module bzrinfogen. * Add bzrinfogen/__init__py which implements the infogen infrastructure. * Add bzrinfogen/big_bash_completion.py: Generates (unusable prototype) bash completion script from internal information on bzr commands and options * Moved bzr_man.py to bzrinfogen/big_man.py and ported it to the new interface. Still missing: * test case for autogeneration * actual implementation of bash completion script