Slight improvement in regex efficiency

git-svn-id: https://plugins.svn.wordpress.org/document-gallery/trunk@1026102 b8457f37-d9ea-0310-8a92-e5e31aec5664
Adding demur's work on improved taxa query (add support for specifying relationship between multiple items in a single taxon)

git-svn-id: https://plugins.svn.wordpress.org/document-gallery/trunk@1026103 b8457f37-d9ea-0310-8a92-e5e31aec5664