Made font on heatmap-pointer tabs slightly smaller at the request of @dwhly

The SearchController.refresh() function has been enhanced in a way that it keeps track of already chosen top-level annotations that way for every annotation we check if the root is already added or not. If added we don't have to add it again. This on
Fixes #849

Fix #845

Adds stickybuttons to the toolbar.

Fixes #831.

Since I can't think of a way to reset specifically to the browser
default font size we'll have to just set the font size explicitly.

Fixes #822

Fixes #820

Fixes #819

This should ensure that after a user decides not to log in their
ongoing edits or highlight switches are cancelled and any partially
entered login details are cleared.

This is so that an ongoing edit does not become a draft until login
is completed. Otherwise, we leak drafts when the login pop-up is
ignored.

On $reset event, authentication model fields weren't being cleared.

- Wait until we have a token to finish on-going edits
- Make sure to reset the on-going highlight switch
- No need to cancel on route change now that draft discarding does that

Prevents losing track of drafts when switching from highlighter to
comment tool if replies have been started in the sidebar.

Refactored the way changing the tool triggers setting visible highlights.
The change should always ensure better interaction if other components
change the tool or highlight state in the future and trigger events.