Clean up commandline arguments

[kasbah]

Would be good to clean up the commandline in non backwards compatible way:

1. Set --recurse and --group to default to true
2. Get rid of--insert and --extract switches, instead:

kifield <extract-file> <insert-file>

If multiple files need to be specified (seems rare now that we have --recurse):

kifield <extract-file-1> <extract-file-2> -- <insert-file-1> <insert-file-2>

(this has some precedence, e.g. with git: git diff [options] [<commit>] [--] [<path>...])