Question Desk 2.27.0

Added

• Question Desk for WordPress. The same Question Desk as a WordPress plugin, for
  organizations that would rather run it on their own site. Both versions are supported:
  neither replaces the other, and the pages, the participant-facing text, the CONFIG values and
  the sessions CSV columns are generated from this app, so a fix to a page or to wording is one
  change for both. It lives in wordpress/; see WORDPRESS.md and
  wordpress/README.md. Nothing about the Apps Script app changes.

Changed

• The guest page (docs/join) can serve either version. A copy hosted for the Apps Script
  app names the deployment in the link, as before; a copy hosted for a WordPress Question Desk
  names that site once in the page itself (data-site), and its links carry no site at all — so
  a link can never make a guest page show some other website.
• A room screen inside a guest page inside the PowerPoint add-in is heard again. The screen
  now reports to window.parent as well as window.top, and the guest page passes that on. The
  add-in can only check the origin it framed, so without this it heard nothing from a guest page
  hosted on another host and reloaded the slide every three minutes.