• Added: CardDAV support.
• Added: An experimental WebDAV client.
• Added: MIME-Directory grouping support in the VObject library. This is very
  useful for people attempting to parse vcards.
• BC Break: Adding parameters with the VObject libraries now overwrites the
  previous parameter, rather than just add it. This makes more sense for 99% of
  the cases.
• BC Break: lib/Sabre.autoload.php is now removed in favor of
  lib/Sabre/autoload.php.
• Deprecated: Sabre_DAV_Directory is now deprecated and will be removed in a
  future version. Use Sabre_DAV_Collection instead.
• Deprecated: Sabre_DAV_SimpleDirectory is now deprecated and will be removed in
  a future version. Use Sabre_DAV_SimpleCollection instead.
• Fixed: Problem with overriding tablenames for the CalDAV backend.
• Added: Clark-notation parser to XML utility.
• Added: unset() support to VObject components.
• Fixed: Refactored CalDAV property fetching to be faster and simpler.
• Added: Central string-matcher for CalDAV and CardDAV plugins.
• Added: i;unicode-casemap support
• Fixed: VObject bug: wouldn't parse parameters if they weren't specified in
  uppercase.
• Fixed: VObject bug: Parameters now behave more like Properties.
• Fixed: VObject bug: Parameters with no value are now correctly parsed.
• Changed: If calendars don't specify which components they allow, 'all'
  components are assumed (e.g.: VEVENT, VTODO, VJOURNAL).
• Changed: Browser plugin now uses POST variable 'sabreAction' instead of
  'action' to reduce the chance of collisions.