KaTeX escapes its own input and we trust it to generate safe HTML as
output. Passing HTML generated by KaTeX through ngSanitize can mangle
the result.  eg. The formatting of the infinity symbol is corrupted when
using this test block for example:

  $$\lim_{x \to \infty} \exp(-x) = 0$$

This commit rewrites the rendering logic to only sanitize the markdown
output from Showdown.

This additionally fixes an issue where text that _happened_ to also
be valid markdown in the rendered math would be rendered as markdown,
which is not what we want.

Create a single instance on the first call and cache it afterwards.

 - Add a test that input markdown is sanitized with ngSanitize

 - Add a test that verifies that malformed HTML is tolerated.

Angular 1.5.x no longer throws an exception when the input HTML is
malformed. This adds a test to catch any potential changes in future and
document the expected behavior.

Fixes #2970
Fixes #2935

Make it easier to verify that rendered content is sanitized correctly by
feeding the final HTML string to $sanitize once, instead of trying to
sanitize pieces individually.

In the process, this fixes a bug with the previous implementation where
inline math was rendered if it started or ended with either '\(' or
'\)'. The new implementation requires that inline math blocks start with
only '\(' and must have a matching '\)'

This logic has now been moved to render-markdown.js

Extract markdown and math rendering out of the editor
component into a separate module and add tests.

CSP Violation: old homepage

Changes the space between items in the group members list. Reduces the space between documents a little, to make them a bit more balanced.

Dev install docs corrections

Scroll share dialog into view when created

These dialogs appear at the top of the annotation list, scroll
them into view if necessary.

The 'scroll-into-view' library is used rather than
Element.scrollIntoView() in order to get smooth animations that are
consistent with how the document is scrolled to selected annotations.

 - Only write to the dialog visibility state in one place
   in AppController.

 - Scroll share and login dialogs into view when corresponding
   link is selected in top bar.

Fixes #3043

Convert the dialog to JS and modernize the style to follow current
component conventions.

Remove empty annotations when a new annotation is created

When a new annotation is created, remove any empty annotation cards that
currently exist. This fixes an issue where it was easy to accidentally
create a large number of blank annotations or empty replies.

Any annotations which are not new (ie. have an ID assigned) or have tags
or text entered by the user are kept.

This logic applies to both annotations and replies.

Merge pull request #3197 from hypothesis/sheetaluk/299-add-a-copy-to-clipboard-button-to-the-share-menu

Add copy to clipboard functionality.

Add basic copy to clipboard functionality so user can use a button
click to copy a direct link to his clipboard, when supported by the
browser.

* Refactor annotation share dialog into a component.
* Add tests for annotation share dialog.

Merge pull request #3216 from hypothesis/sheetaluk/298-add-product-version-and-environment-info-to-the-tool

Show product version and environment info.

Show a dismissable card to the the top of the sidebar containing
information about the version of the tool they have installed as
well as environment information so that we have more information
while troubleshooting errors.

`legacy-site.js` is only loaded on the old home page, so we can safely
add it to that existing JS file.

It lives in it's own CSS file (`styles/old-home.css`) to make it easier
to delete once we remove the old homepage.

Add a helper function for writing parameterized JS tests

 Fix error in session.js when an /app request fails 

Retry requests to /api endpoint

Mocha lacks built-in support [1] for writing parameterized tests and the
suggested solution [2] involves a bunch of boilerplate* which has IMO
resulted in different styles of parameterized tests in our codebase and
not having parameterized tests when they would be useful to attain more
complete coverage.

This adds a helper inspired by [3] for writing parameterized tests and
switches several existing places in our code to use it.

* Though less with ES2015 syntax.

[1] https://github.com/mochajs/mocha/issues/1454
[2] https://mochajs.org/#dynamically-generating-tests
[3] https://github.com/lawrencec/Unroll

Do not expect to be able to parse valid session data out of responses
with 5xx status codes - eg. gateway errors, internal server errors.

Convert admin to package

Fix KaTeX font urls

Dispatch markdown editor input changes from $apply() block

The input event handler's callback was not invoked inside an $apply()
block, so the $digest function was never called to propagate the changes
in vm.setEditText() in annotation.js. This happened to work previously
because ngModel's $setViewValue() was called to apply input changes,
which internally uses $scope.$apply().

This commit wraps the input events from the markdown editor with $apply
but debounces them. Since $apply() triggers every single watcher in the
application, running it on every keystroke causes noticeable lag
otherwise.

Fixes #3212

Replace homebrew background workers with Celery

Handle requests to the /api endpoint that fail with network errors in
the same way as failed requests to the /app endpoint by retrying the
request with exponential backoff until it succeeds.

Otherwise, if the request fails then `store.(Annotation|Search)Resource`
are not populated and code that tries to make API requests fails.

When a request to the session endpoint fails with a network
error, avoid trying to parse the response in process()

Tidy up the 'resolve' object to use `// @ngInject` and add a comment to
clarify what it is for.

Update package.json with the version as-formatted by npm