• Better error message when the browser plugin is not enabled.
• Added a super minimal server example.
• #730: Switched all mysql tables to utf8mb4 character set, allowing you to
  use emoji in some tables where you couldn't before.
• #710: Provide an Auth backend that acts as a helper for people implementing
  OAuth2 helper token. (@fkooman).
• #729: Not all calls to Sabre\DAV\Tree::getChildren() were properly cached.
• #727: Added another workaround to make CalDAV work for Windows 10 clients.
• #742: Fixes to make sure that vobject 4 is correctly supported.
• #726: Better error reporting in Client::propPatch. We're now throwing
  exceptions.
• #608: When a HTTP error is triggered during Client:propFind, we're now
  throwing Sabre\HTTP\ClientHttpException instead of Sabre\DAV\Exception.
  This new exception contains a LOT more information about the problem.
• #721: Events are now handled in the correct order for COPY requests.
  Before this subtle bugs could appear that could cause data-loss.
• #747: Now throwing exceptions and setting the HTTP status to 500 in subtle
  cases where no other plugin set a correct HTTP status.
• #686: Corrected PDO principal backend's findByURI for email addresses that
  don't match the exact capitalization.
• #512: The client now has it's own User-Agent.
• #720: Some browser improvements.
• The zip release ships with sabre/vobject 4.0.1,
  sabre/http 4.2.1, sabre/event 3.0.0,
  sabre/uri 1.0.1 and sabre/xml 1.3.0.