[documentation] Theme developers guide overhaul

[Heine Deelstra]

Dear fellow Drupaleers,

In my opinion, the theme docs could use some love and attention. Perhaps a  
reorganization or even a rewrite.
A stronger focus on learning themeing (how do theme functions work); not  
too difficult, not too dummy *and* a complete reference would be a boon.

I'm envisioning something like the Forms API quickstart guide coupled with  
the Forms API reference.

- A proper introduction to theme functions
- A list of form_ids and corresponding form would be great for themers.  
The list of form_ids is a simple grep -rn drupal_get_form *.
- A list of themeable functions, with arguments and a short description.
- Assorted goodies for phptemplate, smarty etc

As you can see I haven't thought it through yet. This is were you come in.  
Any ideas?
I'm also looking for people willing to work on this. It's fairly large,  
and I'm not sure whether I can do it all by myself.

Regards,

Heine Deelstra