Added support for IPv6 addresses to class IpAddress:

 - For some of the methods, the IP Version needs to be specified by the
   caller. This applies to the IpPrefix API as well.
 - For now, everywhere IpAddress is used and the IP version has to be
   explicitly specified by the caller, we assume/specify IPv4.
 - Added unit test for class IpAddress: for both IPv4 and IPv6 addresses.
13 files changed