v0.8.15

Settings can be saved again

Fixed

• The Save button on the Settings page did nothing. It was drawn, it was enabled, and nothing
  at all was listening for a click on it, so no setting could be saved from any tab — poll
  intervals, notification channels, alert thresholds, which pages are shown, session timeout.
  Reset beside it worked, which is what made the page look normal. Reported as "Appearance Save
  not working", which was simply where it was noticed. Issue #126.
• The "Require sign-in" toggle always showed as off, whatever the install was actually set to,
  because nothing ever read the real value into it. It now shows the truth.

Internal

• A new check refuses any button that only the permissions layer touches. That is the exact shape
  of the last three broken controls: enabled and disabled correctly, wired to nothing, and each
  one found by somebody clicking it rather than by a test.
• Saving a form no longer sends blank password fields, which the server reads as "clear this".