A port providing message transport between two freedom contexts existing in
separate Node.js VMs.  Uses node's 'require("vm")' to generate a separate
namespace with a shared global object for communication. The module-side
implementation is in @see(lib/modulecontext.js)
@class NodeLink
@extends Link
@uses handleEvents
@constructor
function(id, resource) {
  Link.call(this, id, resource);
  this.id = id;
  this.started = false;
}