Update disconnect state.

A connection is disconnected when instanciating.
Consider other servers when selecting connection.

select() can work on different connections, example:

    $server  = new Hoa\Socket\Server('tcp://127.0.0.1:8880');
    $serverA = new Hoa\Socket\Server('tcp://127.0.0.1:8881');
    $serverB = new Hoa\Socket\Server('tcp://127.0.0.1:8882');

    $server->consider($serverA)
           ->consider($serverB);

    while(true) foreach($server->select() as $node) {

        if($server->is($serverA))
            $server->writeAll('response to serverA');
        elseif($server->is($serverB))
            $server->writeAll('response to serverB');
        else
            $server->writeAll('response to server');

        $server->disconnect();
    }

In the example, we see that $server handles all connections.
Node names are also considered. If $serverB->setNodeName('MyNode'), then
in the loop, if $server->is($serverB) implies that $node is an instance
of MyNode.
Welcome Hoa\Socket\Server\Handler \o/!

This class provides a server handler: a complete server skeleton.
We are able to run() a server, to merge() with other ones and to send
messages in different ways (A -> A, A -> B, A -> *\A etc.).