Thanks to @Xon for contributions to this release.
Re-introduce content gifting. Posts, profile posts, profile post comments. Last 2 require XF2.1.
Add missing legacy gift_callback.php endpoint for XF1.x migrations.
Add recently gifted post's widget (can migrate from XF1.x config).
Fixed alerts about received gifts.
Re-add user criteria.
Supports User Essentials "Custom User Upgrade Amounts" for gifts.
Supports Expiring User Upgrades to prevent sending duplicate notifications.
Remove unused options.
Fix potential conflict when trying to gift an upgrade that you already have.