groups: make group management UI less dangerous Don't select the currently chosen group members by default - that makes it less dangerous to hit "remove selected". Also, move the add/remove icons a bit apart and give them titles so the user is less likely to hit the wrong one.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.