Fix "showCode" URL parameter

[ojack]

adding "showCode=false" to the URL should open the sketch with no code visible

also:

• Add this to documentation

[finfinxo]

Hey, I'm happy to try and implement this! Should the menu bar and console be hidden as well I assume?

[ojack]

That's great! yes they should :)

[ojack]

I think it would make most sense to add this in the gallery.js file

hydra/frontend/web-editor/src/stores/gallery.js

Line 43 in bb29d95

setSketchFromURL(callback) {

[finfinxo]

Hey, I've given this a go and it seems to work for me. :) #251