xep: updated XEP-0356 (privileged entity): Several updates according to feedbacks + review: - added links to PEP and namespace delegation XEPs - removed MUST for default values in configuration - <forwarded/> element is now a child of a <privilege/> element - <perm/> "namespace" attribute has been renamed to "access" - "headline" type restriction for "message" privilege has been removed - "message" permission violation now result in a "forbidden" message error - for "presence" permission, only <presence/> stanza with no type or with a "unavailable" type are sent to privileged entity - added specifitation for "presence" if a managed entity is unavailable and if a privileged entity is available after first <presence/> stanzas have been received - added Business Rules section - Updated namespace to reflect incompatible changes