Require texinfo.

Require texinfo.
(defmacro, defgroup): Remove.
(texinfo-section-to-generic-alist): Remove.
Use texinfo-section-list instead (i.e. level is changed string->int).
(texinfo-filter): New function.
(texinfo-chapter-level-regexp, texinfo-subsubsection-level-regexp)
(texinfo-subsection-level-regexp, texinfo-section-level-regexp):
Use it.  And use regexp-opt.
(texinfo-find-higher-level-node, texinfo-hierarchic-level)
(texinfo-update-menu-region-beginning)
(texinfo-update-menu-same-level-regexps)
(texinfo-update-menu-higher-regexps, texinfo-update-menu-lower-regexps)
(texinfo-update-the-node, texinfo-sequentially-update-the-node): Update.
(texinfo-update-node, texinfo-every-node-update)
(texinfo-sequential-node-update): Remove autoload cookie.