• The zip release ships with sabre/vobject 3.1.3, sabre/http 2.0.0alpha5, and
  sabre/event 1.0.0.
• BC Break: The CardDAV and CalDAV BackendInterface each have a new method:
  getMultipleCards and getMultipleCalendarObjects. The Abstract and PDO backends
  have default implementations, but if you implement that interface directly,
  this method is now required.
• BC Break: XML property classes now receive an extra argument in their
  unserialize method ($propertyMap). This allows for recursively parsing
  properties, if needed.
• BC Break: Now using sabre/event for event emitting/subscription. For plugin
  authors this means Server::subscribeEvent is now Server::on, and
  Server::broadcastEvent is now Server::emit.
• BC Break: Almost all core functionality moved into a CorePlugin.
• BC Break: Most events triggered by the server got an overhaul.
• Changed: Sabre\HTTP now moved into a dedicated sabre/http package.
• Added: Support for WebDAV-sync (rfc6578).
• Added: Support for caldav-subscriptions, which is an easy way for caldav
  clients to manage a list of subscriptions on the server.
• Added: Support for emitting and receiving jCal instead of iCalendar for
  CalDAV.
• Added: BasicCallback authenticaton backend, for creating simple authentication
  systems without having to define any classes.
• Added: A $transactionType property on the server class. This can be used for
  logging and performance measuring purposes.
• Fixed: If event handlers modify the request body from a PUT request, an ETag
  is no longer sent back.
• Added: Sabre\DAV\IMultiGet to optimize requests that retrieve information
  about lists of resources.
• Added: MultiGet support to default CalDAV and CardDAV backends, speeding up
  the multiget and sync reports quite a bit!
• Added: ICSExportPlugin can now generate jCal, filter on time-ranges and expand
  recurrences.
• Fixed: Read-only access to calendars still allows the sharee to modify basic
  calendar properties, such as the displayname and color.
• Changed: The default supportedPrivilegeSet has changed. Most privileges are no
  longer marked as abstract.
• Changed: More elegant ACL management for CalendarObject and Card nodes.
• Added: Browser plugin now marks a carddav directory as type Directory, and a
  shared calendar as 'Shared'.
• Added: When debugExceptions is turned on, all previous exceptions are also
  traversed.
• Removed: Got rid of the Version classes for CalDAV, CardDAV, HTTP, and DAVACL.
  Now that there's no separate packages anymore, this makes a bit more sense.
• Added: Generalized the multistatus response parser a bit more, for better
  re-use.
• Added: Sabre\DAV\Client now has support for complex properties for PROPPATCH.
  (Issue #299).
• Added: Sabre\DAV\Client has support for gzip and deflate encoding.
• Added: Sabre\DAV\Client now has support for sending objects as streams.
• Added: Deserializer for {DAV:}current-user-privilege-set.
• Added: Addressbooks or backends can now specify custom acl rules when creating
  cards.
• Added: The ability for plugins to validate custom tokens in If: headers.
• Changed: Completely refactored the Lock plugin to deal with the new If: header
  system.
• Added: Checking preconditions for MOVE, COPY, DELETE and PROPPATCH methods.
• Added: has() method on DAV\Property\SupportedReportSet.
• Added: If header now gets checked (with ETag) all the time. Before the dealing
  with the If-header was a responsibility of the Locking plugin.
• Fixed: Outbox access for delegates.
• Added: Issue 333: It's now possible to override the calendar-home in the
  CalDAV plugin.
• Added: A negotiateContentType to HTTP\Request. A convenience method.
• Fixed: Issue 349: Denying copying or moving a resource into it's own subtree.
• Fixed: SabreDAV catches every exception again.
• Added: Issue #358, adding a component=vevent parameter to the content-types
  for calendar objects, if the caldav backend provides this info.