When the client is embedded in a partner site and a login button in the
client is clicked, call the JavaScript onLogin function that was
provided to us by the partner via the window.hypothesisConfig function.

When not embedded in a partner site, just prompt for a first-party login
as normal.

Note that this means that if the client is embedded in a partner site
with no onLogin callback in window.hypothesisConfig, then nothing will
happen when the login button in the client is clicked.

Separate bridge events sent from sidebar to annotator and from annotator
to sidebar into two separate sections in the source code. Just to make
documentation of the events clearer.

Fix PDF quote anchoring

See https://github.com/hypothesis/client/pull/261#discussion_r103251150

The previous syntax ended up executing:

  docker run -d hypothesis s3://cdn.hypothes.is nickstenning/s3-npm-publish

So `hypothesis` was interpreted as the Docker image name instead of an
argument. Passing the args as the second ('command') argument to
`Image.withRun` results in the correct command being executed:

  docker run -d nickstenning/s3-npm-publish hypothesis s3://cdn.hypothes.is

Upload the client to the S3 bucket behind cdn.hypothes.is after
publishing to npm. The service will then redirect requests for /embed.js
to cdn.hypothes.is/hypothesis

We decided to publish the client's assets to a Hypothesis-specific
domain because publishers (eg. https://internethealthreport.org) may
want to use CSP to restrict where assets are loaded from and they won't
want to whitelist the whole of npm.

This also gives us better control over caching headers used on assets.

Improves performance and includes a number of bug fixes. See
https://github.com/showdownjs/showdown/blob/master/CHANGELOG.md for
changes.

Several tests required small changes because the rendering of
`para1\n\npara2` changed from:

  `<p>para1</p>\n\n<p>para2</p>`

To the visually equivalent:

  `<p>para1</p>\n<p>para2</p>`

This test fails without the `toPositionAnchor` fix in the previous
commit.

This method used to exist in the `dom-anchor-text-quote` library but got
lost when the class was moved to a wrapper in `types.coffee` after the
upgrade to dom-anchor-text-quote v3.x.

This method is used by PDF anchoring and its absence caused quote
anchoring to throw an exception. The majority of PDF annotations still
continued to anchor because the position anchor still worked.

This commit also adds some basic documentation to the `types` module and
some basic API tests.

Make this file easier to understand for the next person who tries to
read it.

The release notes were missing on the GitHub Releases page for the
client for several recent releases. This happened because of incorrect
heading levels used for subsections within a release in the CHANGELOG
file.

Don't treat annotation quotes (TextQuoteSelector.exact) as HTML

The annotation quote, as plucked from the TextQuoteSelector, is not
HTML, and so shouldn't be rendered as such.

Fixes hypothesis/h#2896.

Add invisible threads list to allow render time saving for out of vie…

Add a new entry point script for the client application

Remove account settings and logout link from login control for 3rd pa…

For 3rd party users:
Remove the 'Account settings' link from the account menu
Remove the logout link from the account menu

Related PR:
https://github.com/hypothesis/client/pull/228

Fixes:
hypothesis/product-backlog#141

Disable the link to activity pages from user profile, if the user is …

correcting CC0 terminology

When serving the package's contents via an npm CDN such as unpkg.com, it
will be more convenient if the asset root URL provided by the service
refers to the root of the package rather than the root of the `build/`
dir.

Add additional preversion checks

Before bumping the package version and creating the tag, verify that:

 - Git is set up to create signed tags

 - GITHUB_TOKEN is set to an access token with permissions to push to
   the hypothesis/client repository