[SQUASH ME] basic_net: Let BASIC_NET_CMD_ACK tell the length of an option value
[SQUASH ME] dummy_mac: adapt dummy_mac for previous change
[SQUASH ME] transceiver: organize options for basic_net better
[SQUASH ME] basic_net: SUBNETS might be something else then unsigned value
[SQUASH ME] unittests: Finish tests for BASIC_NET_CMD_GET