topic: support --rev argument and properly process then as user input Revisions inputed by the users should be processed using `scmutil.revrange`. This will take alias into account and allow extensions to monitor the user inputs. As a side effect, the '_changetopics' function takes revisions as argument. make the API clearer.

syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes