sublime text: update preferences to add ruler at 74 characters.

74-character width is best practice for git commits per
http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
and ltovalds.
shell: update `$EDITOR` to use Sublime Text's `subl` in 'wait' mode.
sublime text: add plugin AutoWrap

Add plugin AutoWrap and set the wrap width (80 characters).