RFC: commit message guidelines

[Jordi Gutiérrez Hermoso]

We've never really set down a formal document on how to write commit
messages, and we're all following slightly different styles and ad-hoc
conventions in our commit messages. I think it's good to uniformise
this, so I have begun a wiki page about it:

    http://www.octave.org/wiki/index.php?title=Commit_message_guidelines

Please fix it, edit it, comment on it. When it seems like it's in good
shape, we can add it here:

    
http://www.gnu.org/software/octave/doc/interpreter/Basics-of-Generating-a-Changeset.html

Thanks,
- Jordi G. H.