Fixed taxonomy tabs, save button, and preview. APLQuery_mod fixes.

Fixed taxonomy tabs not displaying text by using the nice name if no
singular name was found. Fixed save button not updating (would keep
displaying 'Saving...'), and added the first ajax function to catch the
errors with an alert dialog. Fixed preview bug adding a null post id
with the dynamic settings.

Also, this lead to other major fixes left from apl_query_mod project.
Fixed List Count, which also change the post limit that would later be
implemented for pagination and there were changes to the total about of
posts queried each query string (with the amount of excluded posts
included to prevent flooding). The post exclude function is also
obsolete now that post_in IDs are filtered before the final query.