* Add Prettier formatting to source files and example files, and check that Prettier formatting is maintained on PRs
* Remove trailing-comma as we are using Node 6 on Circle
* Use latest Node 6 LTS version in Circle
* Remove unused test
Marked had the ability to display html code. This is useful if you want to embed iframes, set size to images... This allows arbitrary html to be embedded with no sanitization, so `<script>alert()</script>` will be executed. This isn't such a big issue since the markdown is written only by contributors.
I also removed the componentWillUpdate call since it's not used (and wrong).
* Add the ability to define a default language
I don't want to have to add the language i'm working on to every single block nor do I want to rely on a default heuristic to find the language.
This adds the ability to write
```
highlight: { defaultLang: 'xxxx' }
```
in `siteConfig.js` to force the language when not specified.
I tested it without a a highlight block, without a defaultLang attribute and with one and with a wrong one. All of them work as expected.
* Move comment around
* Remove client side highlighting
* Update CSS rules to render plain code blocks with expected left border
* Add back codeColor background color config
* Ensure all pre code blocks use Highlight.js classes
