Different syntax for parse tests.
Change check-parse to with-parser
Fix bug with $any-open-tag
Tweak comment
$pre $script $style specializations of plain-body

All should simply parse $anyChar until their close tag.
$block-element need not list specific parsers.

There's no real speed advantage, it's just noise.
Define and use $not-block-element
Say that html head body are "block" elements

Useful fudge for parsing HTML in markdown.
Define $html-document and use with redex-test

The redex tester is really only generating HTML (not markdown) so simply
parse with that, instead.