Don't require `custom'.

Don't require `custom'.
(xml-lite-parse-tag-name): Properly treat non-ASCII chars.
(xml-lite-parse-tag-backward): Obey sgml-empty-tags.
(xml-lite-get-context): Drop nested tags not just for comments.
(xml-lite-indent-line): Be more careful about moving point.
(xml-lite-insert-end-tag, xml-lite-slash):
Use indent-according-to-mode instead of xml-lite-indent-line.
(xml-lite-mode): Make xml-lite-orig-indent-line-function buffer-local.
Set sgml-xml-mode.  Don't call force-mode-line-update.
(xml-lite-mode-map): Don't bind TAB.