Questions about the network implementation

@Ollie: cool, I'd be glad to try it out!

Gordon, I don't really understand why you're so hostile to non-JS additions. I was going to see whether I can insert a C-level sockets API so protocols in C could go through the Espruino sockets layer and thereby be target independent. I really don't see the issue of having more features available on targets that have more flash or RAM and less on others. This wouldn't affect whether Espruino still fits into the original Espruino board.

I looked again at the JS MQTT module and noticed:

      else if(type === TYPE.PUBACK) {
        // implement puback
      }
      else if(type === TYPE.SUBACK) {
        // implement suback
      }
      else if(type === TYPE.UNSUBACK) {
        // implement unsuback
      }

which tells me that it doesn't even implement QoS 1.