MACAddress: Fixed that interfaces were assigned different MAC addresses when multiple runs were executed.

Added a cSimulationLifetimeListener to reset the MACAddress counter before initialize is called.
IPv4NodeConfigurator: Fixed how the routing table is accessed to support multiple network protocols.
IPv6: Fixed visiblity for INetfilter.
InterfaceEntry: Added the missing case for IPv6 to joinMulticastGroup with a TODO.
GPSR: Added code to reset global static state.
GPSR: Added hasPosition to PositionTable.