rename global file handle
code to pull git history, not yet useful
try to produce links to github commits. fail.
utility function
disable versioning code for now
copy Makefile, versions.txt
allow branches other than HEAD to be used
handle ignored files (with a nop)
support for pulling in old trees to import/
more options: skeleton support for updating the import/ tree.
support outputting just the shas of recent changes, to feed into
repo-overlay.pl --apply