Revert "Bind M-[ to paredit-wrap-square."

This reverts commit a26c148244962c1365c185dbe154118c88183575.

`ESC [' is how various terminal escape sequences begin, so overriding
this is a bad idea!
Fix reference to `backward-down-list', which is no more.

(Why doesn't GNU Emacs include this?  Grmble.)
Tweak whitespace in `paredit-split-sexp'.  No functional change.
Rework HTML output to simplify and prettify everything.
Tweak HTML output a little more.
A little more HTML tweaking.  Not perfect, but enough for the day.