Make smart-punctuation faster. See issue #67.

Among other things, Racket's `parameterize` doesn't work in the face of
Parsack's use of lazy evaluation. Instead, add Parsec-style "user state"
to Parsack, and make use of it here.
Allow HTML tags to include hyphen
Single or double quote start only before $alphaNum
Use short fixed list of schemes for autolink

Not as flexible, but faster -- especially wrt not chasing what will
actually turn out to be an HTML tag.
Simplify $spnl

This doesn't fix incorrect behavior, but simpler is better, and perhaps
a bit faster given how much $spnl is used.
Merge pull request #34 from greghendershott/issue-67

Frog Issue 67