Bump mocha from 6.1.3 to 6.1.4

Bump sinon from 7.3.1 to 7.3.2

Bump karma from 4.0.1 to 4.1.0

Bump gulp from 4.0.0 to 4.0.1

Bump babel-plugin-istanbul from 5.1.1 to 5.1.2

Bump enzyme-adapter-preact-pure from 1.12.0 to 1.13.0

Bump preact from 10.0.0-alpha.4 to 10.0.0-beta.0

Bumps [karma](https://github.com/karma-runner/karma) from 4.0.1 to 4.1.0.
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](https://github.com/karma-runner/karma/compare/v4.0.1...v4.1.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [enzyme-adapter-preact-pure](https://github.com/preactjs/enzyme-adapter-preact-pure) from 1.12.0 to 1.13.0.
- [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/v1.12.0...v1.13.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [sinon](https://github.com/sinonjs/sinon) from 7.3.1 to 7.3.2.
- [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/v7.3.1...v7.3.2)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul) from 5.1.1 to 5.1.2.
- [Release notes](https://github.com/istanbuljs/babel-plugin-istanbul/releases)
- [Changelog](https://github.com/istanbuljs/babel-plugin-istanbul/blob/master/CHANGELOG.md)
- [Commits](https://github.com/istanbuljs/babel-plugin-istanbul/compare/v5.1.1...v5.1.2)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [gulp](https://github.com/gulpjs/gulp) from 4.0.0 to 4.0.1.
- [Release notes](https://github.com/gulpjs/gulp/releases)
- [Changelog](https://github.com/gulpjs/gulp/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gulpjs/gulp/compare/v4.0.0...v4.0.1)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [preact](https://github.com/developit/preact) from 10.0.0-alpha.4 to 10.0.0-beta.0.
- [Release notes](https://github.com/developit/preact/releases)
- [Commits](https://github.com/developit/preact/compare/10.0.0-alpha.4...10.0.0-beta.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [mocha](https://github.com/mochajs/mocha) from 6.1.3 to 6.1.4.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mochajs/mocha/compare/v6.1.3...v6.1.4)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Handle illegal group link states

Previously the visibleThreadList state in thread-list did not get
calculated in onInit because the method that did so was subscribed to
after the 'changed' event was emitted. This issue was resolved by
calling the method to calculate the state explicitly in onInit and
only subscribing the event handler for changes that may occur after init.

Add sidebar-content-error react component

Make group selectors more efficient

Ensure that selectors for getting the "My groups", "Currently viewing
groups" and "Featured groups" lists only recompute when the groups state
changes. Previously they would have recomputed when _any_ part of the state changed.

More generally, we should be using `createSelector` rather than
`memoize` whenever we have a place in the app that needs to extract a subset
of data from some larger structure and derive some data from that.

Bump @octokit/rest from 16.23.2 to 16.24.1

Bump mocha from 6.1.2 to 6.1.3

Bump prettier from 1.16.4 to 1.17.0

Bump jquery from 3.3.1 to 3.4.0

Bump enzyme-adapter-preact-pure from 1.10.4 to 1.12.0

Bumps [enzyme-adapter-preact-pure](https://github.com/preactjs/enzyme-adapter-preact-pure) from 1.10.4 to 1.12.0.
- [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/v1.10.4...v1.12.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [jquery](https://github.com/jquery/jquery) from 3.3.1 to 3.4.0.
- [Release notes](https://github.com/jquery/jquery/releases)
- [Commits](https://github.com/jquery/jquery/compare/3.3.1...3.4.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 16.23.2 to 16.24.1.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v16.23.2...v16.24.1)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [prettier](https://github.com/prettier/prettier) from 1.16.4 to 1.17.0.
- [Release notes](https://github.com/prettier/prettier/releases)
- [Changelog](https://github.com/prettier/prettier/blob/master/CHANGELOG.md)
- [Commits](https://github.com/prettier/prettier/compare/1.16.4...1.17.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [mocha](https://github.com/mochajs/mocha) from 6.1.2 to 6.1.3.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mochajs/mocha/compare/v6.1.2...v6.1.3)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Fix npm dependencies make target not re-installing if yarn lockfile changed

The make target used to ensure that npm dependencies are installed when
they change depended on `yarn.lock` but didn't actually run `yarn
install` if only that file, and not package.json, changed.

The target relied on a tool called check-dependencies which pre-dates
yarn. `yarn install` is fast if nothing changed, so just run it
unconditionally.

Open the sidebar when direct-linked group