Suggest commit title in prepare-commit-msg hook

[grembo]

Summary

This is done based on the files affected by the commit. Suggests up
to two ports at a time and goes to "many" from there.

Unintrusive, yet helpful to get the commit title right (forgetting
the convention, typos, or committing a port by accident).

IMHO better than creating a draconian commit hook, nudging
committers to do the right thing by making their lives easier.

This is what I use personally, I was asked in private if there
was a chance to get this into the repo, so I wanted to try at
least. No hard feelings if you feel like this is unnecessary.

Test Plan

echo something >>devel/ice/Makefile
echo somethingelse >>editors/joe/Makefile
git commit -a

[grembo]

Prevent extra empty line when ammending.

[grembo]

Add quoting like in the original template.

Also bring in .arcconfig change from D30162.

[grembo]

Sorry for all the noise, .arcconfig vs. git migration.

[grembo]

@adridg As you've been sending out regular messages about following the commit message conventions. What do you think?

[adridg]

Works for me (with a sample size n=1), having the category/port: already filled in is nice. It demonstrates nicely what is possible.

[grembo]

@mat Next time, please show some basic respect and comment on a review that has been made obsolete by your own contribution (especially since I made it clear that I'm ok if you don't like it).