Fix real-time delete

When receiving a real-time notification about the removal
of an annotation, we emit an annotationDeleted event,
so that all components can react.

Earlier, we emited this event simply with the Annotation
bject that arrived on the wire.

However, some components couldn't deal with this, because
they were expecting to see the 'real' Annotation object,
the ones they already knew about.

So now we do a lookup before emiting the event, and use
the locally found objects instead.

Standardise on userid

This resource request adds a `user_id` query param. But the
corresponding view function doesn't pay any attention to such a
parameter, simply inspecting the authenticated userid to work out whose
profile to provide:

  https://github.com/hypothesis/h/blob/15c39c8b58a8800d7a985c1d29b83fbdb6873266/h/accounts/views.py#L254

Disable extremely slow auto-update of ancient timestamps

When a timestamp is several months old, and we leave
the application around (in a forgotten tab) for
more than three weeks, the usual method of updating
the timestamp fails.

This change works around that by maxing out our timeouts
at 24 days. (This will simply cause us to check the
time in every 24 days.)

Fixes #1952.

I also moved the 5-second minimum to the same time helper.

Load all annotations

To avoid temporary "message not available" cards

Instead of just one search call (with a fix limit),
process the total field from the result of the first
load and while there is still more to load, initiate
a new search query, with the offset property set to
load the remaining ones

Fixes #1948.

Fix class names for the cc font icons

Refactor and fix scrolling - except padding

Small changes here and there

Update copy on password reset forms

Now all copy uses language familiar to those wishing to reset their
password.

This makes the path correct for the rules generated by the icomoon
dashboard.

EnhancedAnchoring plugin:
 - add `getAnchors()` method
 - add `scrollIntoView()` method
 - move some code from the bucket-bar

TextHighlight plugin:
 - get rid of padded scrolling
 - scrollIntoView() no returns a promise

Other:
 - When we click on an annotation card in the sidebar, we need to
   go to the anchor in the document. However, the highlight might
   not exist at this point, so we should look for the Anchor instead.
   So now we call `scrollIntoView()` onthe anchor.
 - The same goes when we click the arrows on the bucket bar
 - Rename `scrollTo` to `scrollIntoView` everywhere.

Switch two-phase anchoring tests to async

One of the pains with working with lazy-rendering platforms
is that events often happen asynchronously.

Now the test suite for two-phased anchoring reflects this
constraint better.

Added tests for two-phase anchoring.

Add a few test cases for Enhanced Anchoring.

API Changes:
 - Introduce the getAnchors() method
 - Make chooseAccessPolicy() public.

Implementation changes:
 - Add the reference pointing to the newly created anchor to
   annotation object right insite the enhanced anchoring plugin,
   instead of in the Monkey code.
 - Fix access to the Annotator class

Added some test cases for EnhancedAnchoring

Restore functionality to toggle the sidebar

Fix reset password exception.

Also removed a couple of unused event handlers.

This clarifies that the method does not actually show/hide the interface
but rather publishes a method across the channel. The host then shows
the frame on response from the sidebar.

Hide activation code input on forgotten password form

Add `ALLOWED_ORIGINS` environment config variable