lib.socketcapture: Remove redundant import
lib.addresses: Minor improvements to IPAddr.inNetwork()

This adds an "in_network" alias for inNetwork (which should be deprecated),
and makes in it a bit more flexible about parameter types.
lib.util: Update some function names

This switches the names of some functions to use the more recent
naming conventions.  Old ones are still available (for now).
lib.util: Add is_subclass()

A more sensible version of the issubclass() builtin.