HTML export: More flexibility for preamble and postamble

HTML export: More flexibility for preamble and postamble

Andreas Rottmann writes:

> Well, the subject says it all -- attached is a rough patch to
> allow more flexibility with the HTML export; I use it like this:
>
>    (defun rotty/homepage-preamble (opt-plist)
>      (insert "<div id=\"header\">")
>      (insert
>       "
>    <div id=\"navbar\">
>    <a class=\"menu\" href=\"/\">Home</a>
>    | <a class=\"menu\" href=\"/Writings.html\">Writings</a>
>    | <a class=\"menu\" href=\"/Software.html\">Software</a>
>    | <a class=\"menu\" href=\"/blog/\">Blog</a>
>    </div>
>    ")
>      (insert (format
>               "<h1 class=\"title\"><a href=\"/\">rotty</a> &gt; %s</h1>\n"
>               (plist-get opt-plist :title)))
>      (insert "</div>\n")
>      (insert "<div id=\"inner\">\n"))