0.4.0

• Update alert notification template
• Add private discussion new post notifcations
• Use queues for notification sending
• Add support for flarum/flags, allow mods to view flagged private discussions (with permission)
• Fix issue creating group-only pds
• Add private discussions link to session dropdown
• Add sort options to private discussion page
• Fix issue where admin cannot send PD from user controls dropdown
• Move creation of private discussions to userpage, to avoid confusion and improve the user experience