v2.1.0

• Mark-as-read also marks e-mails read on the server
  if supported (thanks Andreas Angerer!)
• libnotify plugin: close associated notification when the e-mail
  has been read (single-notification-mode only,
  thanks Dan Christensen!)
• libnofify plugin: correctly identify
  desktop environment (thanks Denis Anuschewski!)
• Misc other fixes and improvements
• Updated translations