A better hackish implementation of ZMQMGContext with single module global zmq_ctx

This allows mixing php threads with zeromq over the cheapest transport inproc:// allowing code like:
````
$zmq=new ZMQMGContext (1,true);
$mainsok=$zmq->getSocket(ZMQ::SOCKET_REP);
$mainsok->bind('inproc://talktomain');

class TestThread extends Thread
{
    public $param;
    public function run(){

        $zmq=new ZMQMGContext (1,true);


        $tomain=$zmq->getSocket(ZMQ::SOCKET_REQ);
        $tomain->connect('inproc://talktomain');
        $tomain->send(.......);
.......
        $rep=$tomain->recv();
    }
}