Email Queuing Enhancements 2.2.0

• Requires php 7.0+
• Now depends on Standard Library by Xon
• Supports XF2.2

• Fix that the email options page would always try to add another template to the "Email templates to exclude (from queueing)" option

• Work-around for queued test email throwing "Instances of XF\Db\AbstractAdapter cannot be serialized or unserialized"
• Require XF2.1+, suggest php 7.2+

• XF2.1 support
  • While XF2.1 now supports retrying sending email on provider error, it gives up fairly quickly