[patch] Update *_usermeta references to the new WP 3.0 *_user_meta

[cnorris23]

WP 3.0 deprecates all *_usermeta functions in favor of the new *_user_meta functions. It's a pretty straight forward change for the update_user_meta and delete_user_meta functions. The new default behavior for the get_user_meta function is to add everything to an array. There is a $single parameter that's been added to the function to allow get_user_meta to behave like get_usermeta, as far as data presentation goes. I've done my best to go through and add 'true' for the $single parameter, so that nothing operates out of the ordinary. However, something may have been missed, so this will need some testing. I'll also do my best to keep up with any changes to trunk that may require this patch to be updated.

[cnorris23]

first pass

[apeatling]

Thanks, this is a valuable patch.

[cnorris23]

Patch refresh.

[djpaul]

(In [3311]) Don't use deprecated delete_usermeta(). Fixes #2294.