Previously it would count the number of source PRs with outstanding
forward ports, which is not the count from the home page so that was
confusing.
Also add counts next to the groups, so teams can be identified at a
glance.
And finally outline the current user in the list, so they can find
themselves faster when they're not one of the top entries.
- add support for authorship (not just approval)
- make display counts directly
- fix `state` filter: postgres can't do negative index lookups
- add indexes for author and reviewed_by as we look them up
- ensure we handle the entire source filtering via a single subquery
Closes#778
* Adds a changelog page, linked from the main, with content
automatically loaded from the source. To avoid conflicts, each entry
is its own file and entries are grouped by the month during which
the update will (probably) be deployed
* The last group (most likely "last update") doesn't have a title, the
rest do.
* Add changelog entries from the last update so it's not too empty.
* Also update the layout for the alerts a bit: remove bottom margin to
reduce loss of whitespace.
