Delete empty gitmodules

[go2null]

• Handle case where this is the first submodule, so it leaves the git repository as it was before.
• Handle case where this is the last submodule.
• Check before declaring victory.
• Code reformatting and re-organization.
• Added option to continue on error to allow cleaning up failed deletions.

NOTE: Not validated on Mac OS X and BSD.

[go2null]

BTW, here is the script I used to test. Not sure where to save it, attaching it here.
test-git-delete-submodule.txt

[spacewander]

Merged. Thanks!