reinabled loop recording bpm scaling for synced songs
Setup new connections for loop export.
Renamed LoopTracker to LoopLayerTracker.
Added LoopFileMixer worker class.
Added partial implementation of file mixing through worker objects.
Added access to config object to file mixer
Implemented basic two-layer mixing
Added debug statements.
more debugging
Fixed missing sf info
Small modifications to try to get mixing working.
Notify loop recording manager that file is done.