generate-working-copy-states: accept depth arguments on command line
Add a parameter to generate-working-copy-states.py that indicates
how many changesets are wanted. This number impacts all the
subcommands. The current 'filelist' subcommand becomes 'filelist 2',
the current 'base' and 'parent' subcommands become 'state 2 1' and
'state 2 2' respectively, while 'wc' becomes 'state 2 wc'.
See earlier patch for motivation.