Feature: Optional stream

[davidandreoletti]

Snapserver can declare source stream as read only such as --stream.source=pipe:///somewhere/fifo?mode=read. However, sometimes the fifo file is not yet created due to race condition at boot time / run time (eg: mpd creates a custom fifo file and snapserver should read from it.).

In that case, snapserver (v0.28.beta1) would fail to start.

Would you consider letting snapserver starts successfully and then "retry" reading from the stream periodically on failures: eg mode=read&retry_mode=on_failure ?