UPnP/DLNA support

[s-celles]

Hello,

Adding UPnP/DLNA support to RadioDroid could be a nice improvement to cast webradios on devices which support such a protocol. May be related to #936

Kind regards

[werman]

That's a good idea.

For our purposes there are two types of UPnP/DLNA devices

1. That support playing from external networks, so we should be able to just pass them a link
2. That do support only a local network, so we would need to proxy the stream.

The 1) should be easier to implement.

As for libraries - https://github.com/ohmae/mmupnp looks like a good candidate.