Change version-numbering system to Perl's Slightly-SemVer approach

The recent release of Net-Z3950-FOLIO version 1.10 was fie so far as the generation of FOLIO artifacts is concerned, but was rejected from CPAN (the standard repository for Perl modules) because the CPAN indexer thinks that version 1.10 is lower than 1.9. This is because even though version numbers as provided as strings, it treats them as floating-point numbers.

We need to change how we number releases of this module so that CPAN accepts them going forward.