xF2 Add-on Subscriber Removed Notify 2.1.7

• Fix upgrading from XF1 versions

• Support Multi Prefix multiple default forum prefixes

• Fix add-on icon in XF2.1

• Only send notices for removed subscribers if they are actually a subscriber

• Fix possible undefined index when saving options with no config setup

• Improve robustness of XF1 config migration

• Fix "Undefined index: recipients " on upgrading from 2.0.x versions

• Fix invalid phrases on user not being found when saving options
• Migrate XF1 options format to XF2 format
• Track users to notify by user id instead of username to reliably handle username changes

• Fix error when deleting a user with a user upgrade via conversations
• If the sending user (or destination forum) is missing, log to the XF error log

• Cleanup how the notification thread/conversation is created
• Do not create notification thread/conversation inside the transaction