1. In routing_table/prefix.rs remove the old Prefix struct and rename VersionedPrefix to just Prefix.
2. Make sure that the Eq trait implementation consider both prefix bits and its version.
3. ordering should be defined as:
4. Update the Hash trait impl for Prefix to include the version in the hashed data.
5. Add UnversionedPrefix and a method to obtain it from Prefix. This is to be used in those (rare) cases where the version number should not be taken into account during comparisons, lookup, and so on.