Contributor Profiles & A Bug Fix Bonanza

In the penultimate P1 development cycle...

* Contributors can now create a public profile.
The alias and headshot show up on their contributions (instead of username and avatar), and the page automatically lists all of their contributions.

* Post links in digest emails will now log you in automatically, bypassing the login step (single use per token).

* Guest authors can now roll back post update times to the previous version, removing their edits from digest emails.
It's a kind of rescue mode for when you forgot to enable Silent Changes.

* New recordings now trigger standard emails, so you won't get any more of those avant garde ones.

* Plus a few minor interface updates, a bit of refactoring and a couple of light automation tweaks.