Multi-use of rtl_tcp

[pe1chl]

To allow the running of more than one program using the stick, it would be nice when rtl_tcp could accept connections from more than one client in parallel. Of course it should honour settings only from one of the clients (the first?). rtl_tcp should just send the captured data to all connected clients.

Furthermore, it would be nice when rtl_fm could connect to rtl_tcp as well.
With the above, it should be possible to run multiple copies of rtl_fm demodulating different signals in the same band.