* Give back one line of ws when showing a diff.
This was requested by several.
* Un-quote DIFF_FLAG, and add DIFF_OPTIONS. This will allow the user to
do more creative things in a mergemaster rc file. Un-quoting is necessary
in order to handle things like CVS Id tags that look like shell variables.
* Simplify terminal width determination.
Suggestions related to ignoring the CVS Id's were taken from several, with
dillon and gad providing particularly helpful feedback.
60462a1f22