Update. `zmq.context`, `ctx:socket` could receive options as last parameter.
Add. basic ZAP example.

```lua
ctx = zmq.context{
  io_threads  = 2;
  max_sockets =252;
}

sok = ctx:socket(zmq.PUB,{
  linger = 0;
  bind = {
    "inproc://pub.test.1";
    "inproc://pub.test.2";
    "inproc://pub.test.3";
  };
})
```