Allow themers to alter body classes

This is a feature request, so bumping to 7.x

Updated patch to work with latest version of HEAD.
I'm fairly new to these things, but as $body_classes is fairly easy to manipulate, though, should we be adding another variable to the mix?

Keeping in sync with head.

Chasing head.

Test failure : #335122: Test clean HEAD after every commit

I agree with McJim (#2), should we really add body_classes_array when we already have body_classes?

The way I see it:

• The body_classes-string is relatively easy to manipulate should themers really want to do this, either through regexes or explode/split/implode. Something like
  

  $body_classes_array = explode(" ", $body_classes);
  // do all kinds of nifty stuff with the classes array
  $body_classes = implode(" ", $body_classes_array);
  

  in the theme layer should do the trick, no?

• Passing classes to the theme layer for other themeable elements seems to follow the pattern of passing them as one string, not an array
• I couldn't immediately think of a use case for this. If theme layer is meant for presentation, why would it add or remove body classes?

@jjeff (or someone else): can you elaborate a bit on how this could be used?

Marking this quick fix since the change is trivial and unlikely to break anything.

The code style is fine and this will break nothing, and I'm the second reviewer, so I am tentatively marking it RTBC.

However, we haven't solved the question of whether this is a useful feature.

That means it's not quite RTBC yet. Maybe ping some folks in #drupal-design or #drupal-themes tomorrow.

Wouldn't this qualify as a dupe of #306358: Add $classes to templates with new theme_process_hook functions.

Yep.