User Mentions Improvements by Xon 2.10.5

• Fix typo blocking user mention emailing

• Ensure duplication mention emails for reports are not sent (requires Report Mention Improvements v2.4.0+)
• Fix user mention emails are not reliably sent

• Fix "Call to a member function isValidRelation() on null"

• Restore UI for opt-in/out of mention/quote emails
• Use correct permission names in options text
• Add "Block mention rendering if the user has no permissions to use mentions" option (default disabled)

• Avoid pushing all post notifications through the job notification system (previous add-on behaviour), while limiting how long for initial replies to be sent.
  • Stock XF takes upto 3 seconds per reply to send notifications., add-on limits to 0.5 seconds.

• Require XF2.1+, remove XF2.0 support
• Fix matching usergroups had lower priority than matching users in backend, where the frontend and XF1 version the user-group had priority

• Do not constantly append ?c=... to user group avatar URL when editing the a user group

• Implement "Send quote emails only on unreplied threads" option which was missed
  

• Support Push notifications with usergroup mentions (changes several add-on phrases & templates)
• Compatibility fix for Report Centre Essentials v2.2.0+
• Fix linking to usergroup mentions in alerts

• Fix mention/quotes email being sent if a user's account state is invalid, or the triggering user is ignored