Generate Universally Unique IDentifier (UUID) for Drupal objects. Current features include: * Automatic UUID generation/loading/deleting for nodes, node revisions, users, roles, files and taxonomy. * Transparently create UUIDs for objects which don't have one. * Pluggable UUID generator backend. * Sub modules to enable UUID for different entities. * API for implemening UUIDs for contrib entities. Please read uuid_ossp/README.txt before enabling the uuid_ossp module.