Add concurrent composite states

src/soon/PlayZustand.java

src/soon/PlayerZustand.java

src/soon/PowerOff.java

src/soon/PowerOn.java

src/soon/Soon.java

src/soon/SoonTestDrive.java

src/soon/SpeakerZustand.java

src/soon/StereoZustand.java

src/soon/StopZustand.java

src/soon/SurroundZustand.java

src/soon/Zustand.java