Cleanup prompted by pull request from ortylp
Merge branch 'cleanup'

Conflicts:
	src/com/falconware/prestissimo/Track.java
Merge branch 'upstream' of https://github.com/ortylp/Prestissimo into ortylp-upstream

Conflicts:
	src/com/falconware/prestissimo/Track.java
Added a few locks around contentious resources and call the onCompletion callback in a new thread.
Rev play store version.
clean thread termination
Merge branch 'master' of https://github.com/TheRealFalcon/Prestissimo

Conflicts:
	src/com/falconware/prestissimo/Track.java