Test: Updated lifecycle tests.
Examples: Renamed IPv4NetworkConfigurator submodules to configurator.
RoutingTable: Fixed IPv4NetworkConfigurator lookup.
ARP: Fixed when there's no IP address during initialize.
TCPBasicClientApp: Fixed socket closing during shutdown.
UDPBasicApp: Added check to skip unresolved destination addresses in.
UDPSink: Added some text output for testing.
IPv4NetworkLayer: Added IPv4NodeConfigurator and updated fingerprints.
InterfaceTable: Changed the way how interfaces are registered.

Interfaces are unconditionally registered from initialize.
Interfaces are no longer registered during node startup.
Interfaces are no longer removed during node startup.
TCPGenericCliAppBase: Changed to allow unresolved destination address when the server is down.
LDP: Fixed bug when there's no IP address yet.
IPv4NetworkConfigurator: Fixed issue when static routes are re-added to the routing table and updated fingerprint.
IPv4NetworkConfigurator: Changed to compute all network configuration only internally and apply them only upon explicit request.
IPv4NetworkConfigurator: Changed how multicast groups are joined and updated fingerprints.
IPvXAddressResolver: Extended interface IPv4 address lookup to also try IPv4NetworkConfigurator.

Fixes when the node is down and interface is not configured yet.