The threadFilter only needs to be tracking the single message in
the container. It is the deepCount that aggregates the results.
There's no longer any reason to cache a __filterResult.

Small style tweaks to the view-sort-overhaul branch

We can still make page comments even when in highlight mode so don't
save these until the user has a chance to edit.

I had foolishly added an angular.noop and then @gergely-ujvari did
the same, but that doesn't work because angular isn't guaranteed
to be loaded outside our sidebar.

This was part of an earlier card refactor but was put aside until we'd
tested it with the text diffs. These have been removed for the moment
so it seems like a good time to try this style out.

This makes it consistent with the annotation timestamp. The next step
is to make all actions focus when the card is hovered.

Move the edit and delete actions back down to the bottom of the
annotation alongside the share and reply actions.

Improve the experience when searching and composing by adding a
freeze function to the thread filter so that edits can freeze their
filter in a deactivated state in order to always match the filter.
This change keeps edits visible all the time and keeps the reply
and show more counts accurate.

Make the annotation and thread markup a bit more semantic and use
this to tweak some margins now that the reply count is below the
actions.

Drop the "<nobody>" placeholder for unattributed annotations and
instead just opt not to show the username or privacy and highlight
indicators.

Change the markdown directive to use an attribute and tighten up
the collapsed thread styles.

Rather than continuing to track the message counts in the thread
controller, make a separate deep-count directive that exports a
getter / setter from its controller that can be used to query and
increment counters that bubble aggreggations up to any deep-count
directive above.

Instead of firing a `threadCollapse` event when threads collapse
and canceling it from the annotation directive when the annotation
is being edited, the deep-count directive is used to track the
total number of messages in a thead, the number of matches found
by the thread-filter directive, and the number of annotations that
are being edited.

Remove most of the injectables from the thread controller and handle
more of the DOM-specific bits in the link function. The controller
becomes even simpler, but the directive needs tests now.

Create a new directive, threadFilter, that leverages the deep message
count feature of the new thread directive, using the searchfilter
and viewFilter services to keep track of the threads that match the
search filters in real time.

Close #960
Close #1109

Rather than traversing all the descendants at every digest of every
level of every thread, propagate updates from leaf nodes to parents
by giving each thread access to its parent thread controller. Digests
are only ever performed at the top level and are debounced so that
during progressive rendering of threads the number of digests is
greatly reduced. Some adhoc experimentation yields a 50% reduction in
digests during thread rendering on top of the performance gain by
not traversing descendants in `messageContainer#flattenChildren` calls
on every digest.

To accomplish the debouncing, the render service now returns a cancel
function making it have the same signature as `requestAnimationFrame`.

Card emphasis on highlight hover isn't supported by the sidebar
right now and we no longer disable annotating in the sidebar.

After I changed it so that it took a callback rather than a scope
the data parameter became rather useless.

Make changes to allow multiple top-level drafts, drafting before
authenticating, keeping drafts while performing page searches,
and replying to search results.

- Factor out the userAuthorize option passed to the Permissions
  plugin into a local function in controllers.coffee.

- Only load the Permissions plugin when logged in so that the
  plugin options do not leak information about the last logged in
  user and unattributed drafts have no user or permissions field.

- When switching to highlight mode, show the sidebar and flash an
  info message informing the user that they will need to log in
  before annotations are saved, but don't prohibit highlighting.

- Simplify the logic in the guest for highlight mode by offloading
  work to the annotation controller. The "inject" property is no
  longer needed. The annotation controller saves drafts of highlights
  if they have no user and persists them to the server as soon as
  the user is set.

- When logging in, the app controller simply loops through all the
  drafts are publishes 'beforeAnnotationUpdated' to give the
  Permissions plugin a chance to fire.

- When initializing the Store plugin, don't perform any search at
  all when not logged in. This change makes "single player" mode
  work even before logging in.

- Allow hiding the sidebar when editing. Simplify the guest code
  that no longer needs to track the sidebar state by listening for
  'annotationEditorHide' and 'annotationEditorSubmit' and the
  corresponding sidebar code that fired these. They're nonsensical
  now because there isn't exactly one "editor".

- Remove the concept of an 'ongoing edit' entirely, simplifying the
  sidebar code even further. Any number of edits are allowed and
  top level ones are not treated specially.

When the Store updates annotation data it only

With this change, the show differences code is completely out for
the moment, but there should be no more unexpected properties on
annotations objects at all.

Fix #1207

I had decided not to do this initially in order to show annotations
that were missing. We'll have to decide how we want to show the holes,
but it's much better if we prune the containers that aren't used so
that we don't end up with empty threads sitting around all over the
place.

The only tricky thing is that when new annotations are loaded we must
thread everything again or existing containers that were lifted up to
the root will not attach themselves to newly loaded parents.

Improve the already much improved page search.

- Rather than binding the render function to a thread, pass the
  render order list in the accumulator.
- Instead of moreTop and moreBottom just use a single property, more.
- More concise everything. What more can I say?

Refactor the page search rendering algorithm for fewer scope
variables, simpler template expressions, camel case, support
for holes in threads, less looping, conciseness and readability.

No longer change routes when the query changes between the Viewer
and the PageSearch controller so that the filtering is near instant.

The annotator service is not a dumping ground for helper functions.

Clean up a number of issues.

- Fix page search, especially for deep results.

- Split thread directive into its own file.

- Clean up the separation between CSS of threads and annotations.

- Separate more actions menu for annotations from thread actions strip.
  Edit and delete in the former. Share and reply in the latter. Cleans
  up controllers quite a bit.

- Refactor both thread and annotation directives.

- Break out progressive rendering service.

- Clean up template variables to use the controllerAs syntax to treat
  controller as the view model.

- Clean up thread collapse prevention during editing.

- Refactor threading to remove the thread property from annotations and
  take ownership of the thread root, removing the need to track many
  things about threading in the App controller.

- Clean up annotation edit cycle and drop the ngModel usage (doesn't
  work well with objects since it does a shallow watch).

- New thread and annotation directives come with full documentation in
  ngdoc style as supported by the dgeni documentation tool.

- Preserve annotations, when appropriate, upon changing authentication.
  Fix #567.