Spinner library

Ok, uploaded the spinner library to GitHub. There's a demo page too. It's a wee bit buggy though. I think the transition events are not firing when the page is hidden.

Even getting it to the current phase was a pain, the interaction between CSS transitions and animations, the DOM, JavaScript and events is flaky at the edges. Once I get an animation or transition going, it works well. But if I want to change some CSS properties in JS with the intent to trigger an animation or transition, it's pretty much guesswork whether it will actually work without glitches.

Hmm... As a workaround, I think I could just create a new element on every show/hide-cycle. That way the animation can't possibly fire one 100% frame before starting from 0%, right?? (This happened on Firefox... or maybe it was an unanimated frame or something. I ended up switching from animations to transitions because of that.)

On Chrome Canary, border-radius and overflow:hidden don't behave like you'd expect. Instead of clipping the contents to the rounded box, it clips on the rectangular box. I don't know why. And sometimes the rendering flickers when using transforms that toggle HW compositing for the page.