IGMPv3: add registerProtocol call()
add fingerprint tests for IGMP
IGMP: restructure IGMP messages
IGMP: maxResponseTime encoded as an unsigned char, fix decoding function
IGMPv3: move set operation methods to the C++ file
IGMP: IGMPv3Query is subclassed from IGMPv2Query

because IGMPv2 routers must accept IGMPv3Queries