* Add a wiki timestamp parser to copyvios/misc.py
* Refactor copyvios/turnitin.py for more sensible structure
* Update templates/index.mako to incorporate diff link/timestamp and
make it clearer that Turnitin is revision-based checking
Add a checkbox to allow searching the EranBot/plagiabot database for
Turnitin results, and display them in a similar form to the on-wiki
EranBot reports if they exist.
Add a new module (copyvios/turnitin.py) to handle fetching and parsing
the EranBot results.
Bug: https://phabricator.wikimedia.org/T110144
TODO: tweak display HTML/CSS; refactor/clean up turnitin.py;
improve dev set-up so it doesn't always default to testwiki
and can test without hardcoding page title