- Patch #6760 by JonBob: refactored the taxonomy module URLs to be nicer, improved the code/Doxygen comments.

  As discussed before, the path "taxonomy/page/or/1,2" becomes "taxonomy/term/1+2" and the path "taxonomy/page/and/1,2" becomes "taxonomy/term/1,2". The most common case of listing nodes attached to a single term becomes simpler, since it doesn't require a meaningless "or" or "and". A depth of "0" is assumed, but a positive integer or "all" can be used. Feeds are available at "taxonomy/term/1+2/all/feed" and the like.

  This iteration of the patch also changes the structure of taxonomy_select_nodes(), since it was not following Drupal conventions. A handful of contrib modules call this function, and will need to be updated. Instead of passing in a $taxonomy object containing parameters for the function, the parameters are passed independently. This simplifies the code quite a bit. The queries were changed to only return node IDs for speed; all results from this function are passed through node_load() anyway, so the extra information returned was discarded. The AND query was also changed to avoid the strange trick and remove an extra query, at the expense of a table join per root term in the AND. This cleans up the code substantially while at the same time enabling the use of AND with a depth parameter.

  TODO: update contribution modules.