Namespace the drafts module

Add namespace capability to store modules

Each module can now opt into being namespaced by exporting the value for "namespace".

Bump katex from 0.10.2 to 0.11.0

Bump gulp-changed from 4.0.0 to 4.0.1

Bump karma-chrome-launcher from 2.2.0 to 3.1.0

Bumps [eslint](https://github.com/eslint/eslint) from 6.1.0 to 6.2.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v6.1.0...v6.2.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [karma-chrome-launcher](https://github.com/karma-runner/karma-chrome-launcher) from 2.2.0 to 3.1.0.
- [Release notes](https://github.com/karma-runner/karma-chrome-launcher/releases)
- [Changelog](https://github.com/karma-runner/karma-chrome-launcher/blob/master/CHANGELOG.md)
- [Commits](https://github.com/karma-runner/karma-chrome-launcher/compare/v2.2.0...v3.1.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [gulp-changed](https://github.com/sindresorhus/gulp-changed) from 4.0.0 to 4.0.1.
- [Release notes](https://github.com/sindresorhus/gulp-changed/releases)
- [Commits](https://github.com/sindresorhus/gulp-changed/compare/v4.0.0...v4.0.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.10.2 to 0.11.0.
- [Release notes](https://github.com/KaTeX/KaTeX/releases)
- [Changelog](https://github.com/KaTeX/KaTeX/blob/master/CHANGELOG.md)
- [Commits](https://github.com/KaTeX/KaTeX/compare/v0.10.2...v0.11.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Add the experimental focus feature to the docs

Fix JS error when searching after creating a page draft

This adjusts view-filter so it can handle draft annotations which can be defined by a missing id.

`npm` is still used by the final deployment process to publish packages
to the npm registry.

Switch default browser for running tests from PhantomJS to headless Chrome

These are no longer needed when running tests under Chrome.

Update our test/CI environment to a modern browser which matches what
our users use and supports modern web APIs and ES language features.

 - Add a Dockerfile which defines an image that includes everything
   needed to run client tests and deployment steps. This image uses
   plain Alpine as the base rather than Debian as this makes it easier
   to update frequently (every 6 months) to get a current Chrome build.

 - Replace PhantomJS with Puppeteer for testing locally and on Travis.
   Jenkins uses Chromium packages from Alpine.

- Fix failing `services/api.js` test

  Chrome throws an error when trying to construct a fetch `Response` with
  a non-null `body` if the status is 204.

- Fix Timestamp and GroupListItem test failures in Chrome

  - Pass required type argument to `Event` constructor
  - Pass valid `timestamp` argument to `Timestamp`. This value is passed
    on to date functions which require a valid date/time string.

- Fix Slider transition test in Chrome

  Since the transition from open to closed is animated, the actual element
  height doesn't immediately transition to 0px. Instead of checking the
  actual height, check the target height specified by the current style
  properties.

  The previous code happened to work under PhantomJS, but was conceptually incorrect.

Change focus mode button label

Change the label when showing everyone's annotations from "Only <name>"
to "Show only <name>". Having the label always start with a verb is more
consistent and hopefully a bit clearer.

Remove "X" icon from toggle button in focus mode

Since clicking the button toggles between two states rather than
dismissing the "focus mode" header, the "X" icon doesn't feel
appropriate, so remove it.

The button's padding has been adjusted to center align the content
following the removal of the icon.

Fixes #1294

Add first iteration of UI to user-focused mode

Bump sinon from 7.3.2 to 7.4.1

Bump browserify from 16.3.0 to 16.5.0

Bump commander from 2.20.0 to 3.0.0

Bump enzyme-adapter-preact-pure from 2.0.1 to 2.0.2

Bump eslint-plugin-react-hooks from 1.6.1 to 1.7.0

Bumps [eslint-plugin-react-hooks](https://github.com/facebook/react/tree/HEAD/packages/eslint-plugin-react-hooks) from 1.6.1 to 1.7.0.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/HEAD/packages/eslint-plugin-react-hooks)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [enzyme-adapter-preact-pure](https://github.com/preactjs/enzyme-adapter-preact-pure) from 2.0.1 to 2.0.2.
- [Release notes](https://github.com/preactjs/enzyme-adapter-preact-pure/releases)
- [Changelog](https://github.com/preactjs/enzyme-adapter-preact-pure/blob/master/CHANGELOG.md)
- [Commits](https://github.com/preactjs/enzyme-adapter-preact-pure/compare/v2.0.1...v2.0.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [browserify](https://github.com/browserify/browserify) from 16.3.0 to 16.5.0.
- [Release notes](https://github.com/browserify/browserify/releases)
- [Changelog](https://github.com/browserify/browserify/blob/master/changelog.markdown)
- [Commits](https://github.com/browserify/browserify/compare/v16.3.0...v16.5.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [commander](https://github.com/tj/commander.js) from 2.20.0 to 3.0.0.
- [Release notes](https://github.com/tj/commander.js/releases)
- [Changelog](https://github.com/tj/commander.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tj/commander.js/compare/v2.20.0...v3.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [sinon](https://github.com/sinonjs/sinon) from 7.3.2 to 7.4.1.
- [Release notes](https://github.com/sinonjs/sinon/releases)
- [Changelog](https://github.com/sinonjs/sinon/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sinonjs/sinon/compare/v7.3.2...v7.4.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Update user-focus store, rootThread intergration for clarity