Do not consider 0.0.0.0 as an IP broadcast address.
Added const keywords to send(to) api calls
Merge branch 'master' of github.com:tass-belgium/picotcp
Improved implementation of ZMQ and ZMTP

* Parses the header
* Works for both publisher and subscriber

Tested:
* Subscriber (on PIC24F) to python publisher was working
* Publischer (on PIC24F) to python subscriber crashed on the PIC

* Don't trust any code in this file. It's still under heavy development
* and cleanup