Turn `rudp` into a streaming library

[shovon]

As was tangentially discussed in #7, rudp would become a much better library if it had support for streaming. /cc @mvayngrib

[hoffmabc]

:+1:

[swordfeng]

I think it's may be more better if it becomes a seqpacket (sequened packets) protocol. Then the data remains in packets and can be used as stream.

[shovon]

@swordfeng Let's make it a seqpacket and streaming, then.