Collections take 2 frames to render

[stephband]

Because sparky.create() children render on the next frame, and calls to that inside 'each' are also queued to the next frame, that's two frames to render a collection.

Either:

• Make each render without delay, on every collection change (bad)
• Make new Sparkies render immediately, which involves moving the throttle out of .parse and into Sparky() constructor (probably quite a good idea)
• Make new child sparkies render immediately, same as above but with conditional render (probably unecessarily complicated)