Support creating regions via dragging

[tomekr]

Hello! Would it be possible to add support for creating Regions with dragging via enableDragSelection and (i believe) the region-created event?

More info/example here: http://wavesurfer-js.org/example/annotation/index.html

[dschoon]

Hey @tomekr, thanks for the suggestion!

This annotation tool is cool. They must've added this example recently because I haven't seen it before. I have noticed Wavesurfer has been making a number of improvements over the last couple of months.

I'll investigate adding it this weekend.