- compton-trans: Allow reading opacity value from positional arguments,
like the version in master branch.
- compton-trans: Quit when meeting an unrecognized option.
Rewrite a part of compton-trans in order to provide more friendly
error messages, to support window title that contains spaces, and to
limit the number of xwininfo calls to a constant. Not much tests are
done, and I don't know bash well, so bugs could very well exist.