Consolidated PR for Wordlist OO api, Lingua::EN::Inflect and stopword list revisions

This implements the proposed OO API for the wordlist, refactoring functions from Pod::Spell into Pod::Wordlist.

In includes the Lingua::En::Inflect change as well as the stoplist revisions including dagolden words, deduplication, depluralization, etc.

Picks up a dependency on Class::Tiny because that makes Pod::Wordlist objects trivially easy to implement.

Not included: tidying and debug message rationalization