Support multiple sockets, UDP and multicast

[bjoernQ]

Fixes #76

• add support for UDP sockets
• add support for multicast groups
• update dependencies

[ImUrX]

when is this getting merged, i really need the updated dependencies xD

[bjoernQ]

hopefully it will get reviewed and merged later today - we really want to have every small change smoke-tested at least

but since this crate is currently only available via a git dependency you can also temporarily just use the fork/branch - but it should get it today anyways

[bjoernQ]

@jessebraham Mind testing the examples on all the supported targets with your setup? I don't expect problems but would be good to double check this

[jessebraham]

Seems to be working for all examples on my network. The ESP32-S2 seems to be incredibly slow and often hangs on Wait to get an ip address, but I think that may have already been the case, I can't recall.