Add node support for UDP

[Hywan]

Hello :-),

This issue is the next episode of this one #10.

[Hywan]

Normally we should even revert #10 when this issue will be fixed.

[Pierozi]

Hello :)

If we want implement Node for UDP, that require to make ourself an ACK between server & client.
Because like UDP are connectionless, we need send data in socket if we want know new client or know if client timeout.

First problem is, that mean client need use same ACK protocol, and like Hoa is oriented Library, I don't know if is right place. Because in lot of time, UDP client will not be write with Hoa.

[Hywan]

What is ACK?

[Pierozi]

Ack (acknowledgement) signal in TCP/IP.
After some explication on IRC, we don't need handle same node system as TCP, we can limited select as an iterator of UDP client without register node in internal stack.

In same time we discover as we can't specify remote when we want write.
The remote of last read are selected by default.
https://github.com/hoaproject/Socket/blob/master/Connection/Connection.php#L858

I can write a PR.

[Hywan]

ping?

[Hywan]

ping?