org-e-html: Allow to set preamble/postamble in OPTIONS line

contrib/lisp/org-e-html.el

@@ -117,7 +117,6 @@
   ((:agenda-style nil nil org-agenda-export-html-style)
    (:creator "CREATOR" nil org-e-html-creator-string)
    (:convert-org-links nil nil org-e-html-link-org-files-as-html)
-   ;; (:expand-quoted-html nil "@" org-e-html-expand)
    (:inline-images nil nil org-e-html-inline-images)
    (:link-home "LINK_HOME" nil org-e-html-link-home)
    (:link-up "LINK_UP" nil org-e-html-link-up)
@@ -125,10 +124,9 @@
    (:style-extra "STYLE" nil org-e-html-style-extra newline)
    (:style-include-default nil nil org-e-html-style-include-default)
    (:style-include-scripts nil nil org-e-html-style-include-scripts)
-   ;; (:timestamp nil nil org-e-html-with-timestamp)
    (:html-extension nil nil org-e-html-extension)
-   (:html-postamble nil nil org-e-html-postamble)
-   (:html-preamble nil nil org-e-html-preamble)
+   (:html-postamble nil "html-postamble" org-e-html-postamble)
+   (:html-preamble nil "html-preamble" org-e-html-preamble)
    (:html-table-tag nil nil org-e-html-table-tag)
    (:xml-declaration nil nil org-e-html-xml-declaration)
    (:LaTeX-fragments nil "LaTeX" org-export-with-LaTeX-fragments)