[FR] Route input stream to multiple outputs

[maxsharabayko]

There were several requests to send received data to multiple outputs.

See SRT issues 396, 574.

srt-xtransmit route udp://:4200 --output srt://:4201 srt://:4202 udp://192.168.0.1:4500 srt://192.168.1.15:4300