When started at boot as a service discovery may fail due to it
trying to bind to interfaces before the network is actually up.
This could be prevented in systemd by starting the service after
network-online.target but it requires that a wait-online.service is
also enabled which is not always the case since a wait-online.service
can potentially hang the boot process until it times out in certain situations.
This allows for discovery to retry every 10 secs in the 1st 60 secs of uptime
before giving up thus papering over the issue and not holding up the boot process.
This should fix remaining cases of a client connecting, and failing
to start playback from *beyond* the beginning when `librespot` is
still loading that track.
This undoes the `suppress_loading_status` workaround from #430,
under the assumption that the race condition reported there has
since been fixed on Spotify's end.
Include a systemd.service file to run as a user
This new `systemd.service` file allows running and controlling the service as
an unpriviledged user (generally, as part of a user session).
Some of the feature flags librespot uses are not really additive but
rather mutual exclusive. A previous attempt to improve the situation
had other drawbacks, so it's better to postpone a decision and restore
the old behaviour.
Librespot-connect uses hyper anyway, so no one needs to disable it
only to reduce the number of dependencies. Furthermore, when using
another backend, people will use --no-default-features and will forget
to enable the apresolve feature again.
Probably more simple than the previous approach which
doubles the code: Instead of implementing the `Open` trait,
we simply use custom SinkBuilder, one for the default host,
and one for the "jack" host.
