firmware:
- at startup of the firmware, check if an RR-Net MK3 MAC can be read from the
  clock port, and use that one instead of the hardcoded MAC address
- also check if the MAC is already set and dont set it again if so, that allows
  proper usage on chameleon

mk3flasher:
- warn if MAC does not match
- include dumper
- error message on "file not found"
- should check if flash jumper is set
- more verbose test-for-mac routine (instead of DF0C and 9FFC)