sort wordlist case insensitively
remove duplicates
collapse different cases to lowercase
add dagolden's stopwords (with some case collapse)
check stopwords without trailing q{'s}

I've removed them from the wordlist as well.  In some cases, I don't
know why they were there.  I would expect a spellchecker to deal
with a trailing 's for any noun but there were some things like
that in the list ("probe's") nonethless.
use lingua-en-inflect to handle plurals in wordlist
Make Pod::Wordlist a class to manipulate the wordlist

This removes direct access to the global and replaces it
with a wordlist object API.

Side benefit: wordlist changes are isolated to a single
object of Pod::Spell (becaue a new wordlist object is created).
Also people could theoretically create their own wordlist objects
and pass them to Pod::Spell and everything will just work.
make stopword hash values undef to save memory

We check for existence, so we can use undef instead of needing
so many extra scalars as hash values.
mostly shrink the wordlist

Now that we have Lingua::EN::Inflect pluralizing everything in
the wordlist, we can consolidate to singular forms.  Some
non-standard plurals are kept ("gotos").  Also added a couple
acronyms I was suprised were missing.