Implement --close

[eminence]

This option causes the sending side to not send any data and instead immeditally send an EOF. This can be useful when you are only interested in sending data in one direction.

Closes #10

[eminence]

bikeshed: the --close name was picked based on this comment but maybe there's a better name for this argument.

[rklaehn]

Hm, --close is confusing I think. --one-way is better, but it also is not clear which way, given that the listener could send or receive data. How about something like --recv-only or --send-only?

[dignifiedquire]

maybe --once ?

[eminence]

--once also feels confusing to me.

Is --close-stdin any clearer?

--recv-only is also nice

[rklaehn]

I think --recv-only is nicest. It leaves the door open for --send-only if we ever need it, and can be used on both sides if ever needed.

[eminence]

Any other suggested changes on this PR?

[dignifiedquire]

Thanks, sorry for the delay

[eminence]

Thanks!