Added check to skip unresolved destination addresses.
Changed interface handling wrt. lifecycle operations.

Interfaces are unconfitionally registered in initialize.
Interfaces are no longer deleted when the node shuts down.
Interfaces are no longer registered when the node starts up.
IPv4NetworkConfigurator: Better support for lifecycle operations.

The expensive computation of the network configuration is always done only in internal data structures.
The actual changes can be carried out later or immediately, and also any number of times.
Test: Added and modified a number of lifecycle tests.
Added some text output for testing.
Fixed a test config name.
new IPv4 network/node configurator