better CamelCASE support for naming=v8

better CamelCASE support for naming=v8

The previous method of splitting CamelCase identifiers did not work
identifiers containing words in all caps, such as 'VLANValidID'.

Use 'wordsplit' from String::CamelCase which handles these types of
identifiers correctly for naming=v8 mode, while preserving the old
behavior for v7 mode for monikers, column accessors and relationship
names.

New features related to multischema support also use the v8 mode
implicitly.

Add t/80split_name.t to test the 'split_name' utility sub from ::Utils,
at the heart of this change; for both v8 and v7 modes.