[themes] Extra custom theme settings

[Rowan Kerr]

According to http://drupaldocs.org/api/head/function/system_theme_settings
I got the impression that defining a <themename>_settings() (along
with <themename>_features()?) function would allow extra fields to be
inserted on admin/themes/settings/<themename> page but that doesn't
seem to be working for me.

I put _features() and _settings() in template.php but nothing seems to
be happening. I'm probably just overlooking something obvious at the
moment.

What I'd like to do is add an option to allow re-ordering of the
different properties of node and comment through the settings. So that
the site admin could define an order of title, submitted, terms,
content, links... or title, content, submitted, terms, etc without
having to create a new theme or mess with .tpl.php files.

Anyone have suggestions?