some refactoring
fix rms calculation
remove displayed waveform when track stopped
Merge branch 'master' into dev
removed unnecessary variables
fix possible seg fault
fix possible race condition
update PKGBUILD
Merge branch 'master' into dev

Conflicts:
	PKGBUILD
	waveform.c
some refactoring
Merge branch 'master' into dev

Conflicts:
	waveform.c
minor refactoring
unregister widget on disconnect
middle click toggles play/pause