* lisp/htmlfontify.el: Make it obey the font-lock-face text property.

* lisp/htmlfontify.el: Make it obey the font-lock-face text property.
Miscellaneous cleanup such as:
- Don't hide expressions after a closing paren.
- Move initial setq into let.
- Hoist common parts out of ifs.
(hfy-p-to-face, hfy-p-to-face-lennart): Remove.
(hfy-face-at): Use get-text-property instead.
(hfy-prop-invisible-p): Use invisible-p if available.
(htmlfontify-manual): Use \\[...].
(hfy-html-quote-regex): Use [...].
(hfy-combined-face-spec): Simplify.
(hfy-compile-face-map): Don't presume point-min==1.
(hfy-css-name, hfy-buffer, htmlfontify-buffer): Use \' rather than $ to
match end of string.
(hfy-text-p): η-reduce.
(hfy-tags-for-file): Receive cache-hash directly.
(hfy-mark-tag-names): Adjust call.