Fixed `resume`

Invoking `pause` didn't actually pause the event stream, it stopped the entire RAF loop. In other words, calling `resume` on a paused stream had no effect. The fix was to place `emit` inside the `paused` check, and move `_raf` out.

I'm not sure if you're satisfied with this solution, or if you'd rather just restart the raf-loop on `resume`. Let me know and I'll update the PR.