changelog: show merges as semi opaque in more places Follow up to 8c5d1e94f9ee. PRs available for updates (those that have a radio button) are not greyed out - that would make it look too much like they were disabled. These merges should perhaps be shown in a different way - perhaps not greying the whole line. But for now, this makes it more consistent.

# 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
.