Use cadence-session-start as wrapper for specified session.

Fixes problem with unavailable jack and ladish, which sometimes just used other session bus, that supposed for user session.
multi-tool bugfix: Lookup only for processes, started by current user
stopAllAudioProcesses(): Fix termination awaiting code
stopAllAudioProcesses (): Move process termination awaiting code to function
stopAllAudioProcesses(): Parallel termination of both process sets at once