write proper docs (asciidoc format for git compatibility)

	delete tempdir

	--annotate-sometimes: only annotate if the patch also changes files
	  outside the subdir?

	'git subtree rejoin' option to do the same as --rejoin, eg. after a
	  rebase

	"-s subtree" should be given an explicit subtree option?

	--prefix doesn't force the subtree correctly in merge/pull

	add a 'push' subcommand to parallel 'pull'

	add a --squash option so we don't merge histories but can still split
	
	add to-submodule and from-submodule commands