ILI9341 Performance Improvements

Thanks - I really want to get these kind of things sorted - as you say, they're pretty minor (and often easy to fix) but they effect the overall impression of the interpreter. If you paste some JS code in, you expect it to work.

The do...while thing is now fixed, and will be in 1v72. It was actually a symptom of a bigger issue, so I'm really glad to have that fixed.

I'm still working on fixing the precedence thing - it's interesting, as I'd believed that & and | had equal precedence, but it turns out they don't. It seems it's even the same in C as well. I guess I'd never come across it because I tend to bracket things if precedence wasn't obvious - you learn something every day :)