Total pattern drawing refactor, transport planning for better clock

* draw pattern grid and playhead separately
* draw with native canvas methods because paper.js' overhead costs too many ms in processing between frames
* plan for better vinyl search methods and better audio scheduling using .start(s) and interval for
  scheduling sounds instead of an immediate, time-sensitive traverse on the vinyl
  based on: http://www.html5rocks.com/en/tutorials/audio/scheduling/