* docs: added fiddle support for code samples in quick start guide and features
* docs: removed excessive fiddle links for not final steps
* docs: added eof newlines to fiddle examples
* docs: reworked fiddle examples to be more self-sufficient
* docs: reworked fiddle examples according to mentions
* docs: changed http to https in the offscreen rendering fiddle
* docs: fix recent documents fiddle to be more consistent
* docs: add references to app.whenReady() in isReady
* refactor: prefer app.whenReady()
In the docs, specs, and lib, replace instances of `app.once('ready')`
(seen occasionally) and `app.on('ready')` (extremely common) with
`app.whenReady()`.
It's better to encourage users to use whenReady():
1. it handles the edge case of registering for 'ready' after it's fired
2. it avoids the minor wart of leaving an active listener alive for
an event that wll never fire again
