xF2 Add-on Expiring User Upgrades 2.2.1

• Prevent errors when user email preferences have not been correctly setup by the add-on installer
• Improve installer to ensure user email preferences are setup as expected

2.2.0 - Bugfix & XF2.2 compatibility update

• Fix "Extend Upgrade button" option not being respected
• Require XenForo 2.1+
• Require php 7.0+
• Now depends on Standard Library by Xon (v1.1.0+)
• Confirm XF2.2+ support

• Fix poor phrasing when reporting why an upgrade can not be extended

• Fix conversation phrases for payment reversal of extended upgrades/subscriptions
• Update 'Notify user by' list of phrases to include payment reversals for extended upgrades/subscriptions

• Fix "Leave notify conversation on submit" applying to the recipient and not the sender
• Fix 'extend' button not working as expected

• Fix "can extend" check for user upgrades created in XF1.x
• Fix "Shows the reason an upgrade can not be extended" option not actually showing anything
• Add icon the add-on options

• Correctly detect existing subscription for the "Notify user upon extending a recurring user upgrade/subscription?" feature

• Fully fix "Leave conversation and ignore future messages" option for user upgrade conversation notification