feat(core): update react styleguidist to 9.4

[elevatebart]

• Adds support for es6 imports
• make new option simpleEditor to only load the simple react editor and prism.js for even smaller bundles

[elevatebart]

I can as well override the Editor component to bring back codemirror if you prefer.
@rafaesc what is your take on it ?

[rafaesc]

@elevatebart I think that we can maintain the same library of rsg, if it doesn't affect the current view

[elevatebart]

@rafaesc do you mean to have the same editor as React-Styleguidist (breaking change) or to keep CodeMirror ?

[elevatebart]

I made usage of the simpleEditor opt-in so that everyone can switch at their pace... no need for a major version.

[rafaesc]

@elevatebart ok I see that you are still using CodeMirror, well I wanted to use Prism because there are interesting websites that use it, but its fine also CodeMirror

[elevatebart]

@rafaesc I actually want to use both. the simpleEditor option is now documented

[elevatebart]

@rafaesc, I removed all the fat from there. Only 2 parts to see, the addition of the new editor, code & documentation and the adaptation to the React-styleguidist folder structure (add lib/ everywhere)

[elevatebart]

And the rsg-component-default alias of course