Chore: Update Cypress config for a new version

Fix: Slot onClick passes correct ID (styleguidist#972)

Fixes styleguidist#971

Refactor: Split new CodeEvaluator component out from Preview (stylegu…

…idist#976)

Fixes styleguidist#975

Fix: Add editorConfig to Editor, make Editor update when read only (s…

…tyleguidist#974)

Fixes styleguidist#973 styleguidist#979

Fix: Object.entries is not a function in Node 6

Fixes styleguidist#963

Docs: Display source code of any file (styleguidist#964)

Fix: Export Markdown overrides to support easier subclassing and conf…

…iguration (styleguidist#954)

Fix: Add `reduce_funcs: false` to Uglify for Preact compatibility (st…

…yleguidist#940)

Fix: Don't report 'On your network' on localhost (styleguidist#934)

When explicitly setting the serverHost to 127.0.0.1 or localhost,
urls.lanUrlForTerminal is undefined. It makes no sense to print out
undefined, therefore only show the 'On your network' line when it's
defined.

Fix: Ignore mini-html-webpack-plugin (styleguidist#938)

Fixes styleguidist#937