Strawman implementation of blinking cursor in text input + animation 'WaitUntil'

[twitchyliquid64]

This is just a demo, I agree we need to wait until we have a better idea of the API before we tackle animations

Anyway, this is what it would look like to hack it in XD

A few lessons here:

1. Adding stuffing into draw() is a pain in the ass, theres over 80 instances to update XD
2. Adding stuff into draw() is probably a bad idea - the current event loop in application.rs seems to assume state changes only happen on update(), and draw() just, draws. The concept of 'next draw me at X moment/event' doesnt neatly fit into either.

[twitchyliquid64]

Closing this as its obsoleted by #560