Some fixes for behringer x32 module after initial testing

* Fixed type where we were sending to our source port and ip instread
of destination port and ip. This was in both waves and the controller
sketch.
* Fixed issue where analog input was too sensitive and would fluctuate
too much. We now don't send a message unless the fader has moved more
than about 2%.
* Some other code tidying, and comment improvments.
* Added code for dhcp address allocation. This is disabled, because it
didn't seem to actually work. It might work better in another network.