Code folding in editor pane

[lauriejones]

Playroom use has really taken off at nib! The adoption within the UX team especially has been really exciting to see. 👏

A piece of feedback that has come from one of our designers is that when dropping in lots of components to a playroom demo, the code panel can get code heavy quite easily.

"It would be great to have a collapse / expand of elements (similar to how you can in editors like Sublime) to make it easier to see what you’re working on."

CodeMirror has an addon for code folding that I've managed to get roughly working locally:

Code: master...lauriejones:master

Is this something you would be interested in seeing in playroom? I am conscious of how restrained the interface is and this is adding another element to the mix but given the feedback from designers who may be overwhelmed by seeing a wall of code I think there is definitely value here.

Please let me know if this is something I should put a PR together for, and if so any guidance on how the UI should look/behave.

Thanks!