2.1.0rc1

This release is compatible with version 2.0.0.

• Built-in web interface for creating and managing address books and calendars
  • can be extended with web plugins
• Much faster storage backend
• Significant reduction in memory usage
• Improved logging
  • Include paths (of invalid items / requests) in log messages
  • Include configuration values causing problems in log messages
  • Log warning message for invalid requests by clients
  • Log error message for invalid files in the storage backend
  • No stack traces unless debugging is enabled
• Time range filter also regards overwritten recurrences
• Items that couldn't be filtered because of bugs in VObject are always
  returned (and a warning message is logged)
• Basic error checking of configuration files
• File system locking isn't disabled implicitly anymore, instead a new
  configuration option gets introduced
• The permissions of the lock file are not changed anymore
• Support for sync-token
• Support for client-side SSL certificates
• Rights plugins can decide if access to an item is granted explicitly
  • Respond with 403 instead of 404 for principal collections of non-existing
    users when owner_only plugin is used (information leakage)
• Authentication plugins can provide the login and password from the
  environment
  • new remote_user plugin, that gets the login from the REMOTE_USER
    environment variable (for WSGI server)
  • new http_x_remote_user plugin, that gets the login from the
    X-Remote-User HTTP header (for reverse proxies)