Released "Strum Machine 2.0"

Note to self: smaller, iterative releases are best! These monster releases have a way of snowballing out of control...

That said, it may not have been avoidable here, since there was a big UI change (a total rethinking of some things) and I wanted to have one big change versus a bunch of changes that people would constantly have to adjust to. And I wanted to make my UI changes now so that I would be prepared to add new features in the future without affecting the UI.

Also included some oft-requested features, like the ability to make lists of songs (which is now a core feature).