diff colorization: finish highlighting trailing whitespace

color: diff colorization This colorizes diff, qdiff, log -p, outgoing -p, incoming -p, and tip -p.

color: add --color switch --color works like GNU grep --color. --color=auto only colorizes output for non-dumb terminals that are TTYs.

mq: filter out empty commit messages in qfold

mq: drop copy sources removed during qfold (see issue1405)

inotify: do not complain that inotify is not running if autostart is False