[ipv6calc] Release 3.1.0 - Enhancements

Hi all, version 3.1.0 was released, already available as preview on - Fedora Rawhide - Fedora 33, 32 - EPEL 7, 8 Minor Features: * Improve revnibble handling (TLD+NLD given given -> prefix, missing -> suffix), add related online help * add support for compressed IPv4 addresses, like 10/8 (contributed by @grayed) Fixes: * Improve autodetection of nibble strings, add additional test cases, triggered by #19 General: * internal databases: update Visit the release page <https://github.com/pbiering/ipv6calc/releases/tag/3.1.0> to download them. Regards, Peter