Simplify highlight visibility toggling.

Sort orphan placeholders to bottom of stream

setVisibleHighlights was previously two methods disguised as one, behind
the "notify" parameter. This commit moves all the code related to
actually changing local state into the onSetVisibleHighlights handler,
making the setVisibleHighlights function responsible solely for firing
the event.

This makes it possible to call instance methods on the current plugin
from event handlers, without the additional indirection through
window.annotator.

Fix #1618

As discussed in https://github.com/hypothesis/annotator/pull/78.

Fixes https://github.com/hypothesis/h/issues/1598.

stats: Use statsd client for collecting auth metrics

Check to see if an annotation has multiple titles

Fixes the issue where a document title appears in square brackets.

Use the icon font for the adder

Move to using a Chrome browser action

Update the last login date for users

Post install onboarding page

If the firstRun option is provided to the hypothesisConfig.

This saves the implementor redefining the defaults if they only want
to override one or two options.

Get rid of the inAdderClick logic

Instead of setting/resetting the inAdderClick flag,
we can just override mouseUp on the adder click,
and stop propagating.

Update Annotator PDF plugin to support latest PDF.js in FF34

Remove console.log statements from within the app

Log statements do not belong in production code.

Don't swallow exceptions when scanning the document

According to @csillag, there are no good (i.e. non-exceptional) reasons
why `this._scan()` should throw an error. As such, should not be
catching and swallowing the error, as this will make it much less likely
that we receive bug reports about brokenness in dom-text-mapper.

Inspired by conversation in #1596.

Add link to terms of service on create account form.

This update brings support for PDF.js v1.0.712, and thus FF32.
Closes #1592.