* Check and restore .git/MERGE_HEAD if it exists

* Check that current branch is not (no branch)

* "amend" screws with the reset stuff

Check Makefile vs Makefile.PL modification times for re-run.

Also tidy up on renames, as they show up only as renames even if the
file got modified as well.

* Detect modified .perltidyrc or .podtidy-opts files and error out