Modify commit to allow a single-line message to output multiple lines, for better commits.

[chriscorwin]

I am envisioning something like a double pipe (||) as a delimiter to allow commit to format a commit message, splitting the message at each || with linebreaks.

This will allow a single line commit message to have a subject and a body, so that commit messages can still be easy to enter but be formatted properly.

Inspired by this article on Git commits.