gracefully handle clients with wrong samplerate
currently, the first client that connects to a tpf-server defines the samplerate. all other clients must use the same samplerate, otherwise everything explodes (or so; i don't know. but once i connected to the zhdk server with my client running at 44.1kHz, people started yelling at me that i should leave).
this is somewhat related to #2 (closed) , but as a first step it might be enough to just