c++11!
looping by beats, new controls
when loop is enabled, just change length not position

logic should go in controller not view though..
note
moved more looping logic into audiomodel
disabling loop buttons on load
loop shift now repeatable
loop beats now uses an index, not a direct value

this will make midi mapping easier
loop 'now' if we reduce the number of beats in a loop.

really, we need to do this on the audio side..
more intelligent looping, less skipping around
more intelligent loop shifting

seeking to stay in loop so we don't have weird jumps and timing issues
if we shift back
growing and shrinking running loop from start
policy to resize playing loops from start or end or where you are
increased seek fade time, fixed crash on shift
added some more beat loop lengths