Direct Message Monitor. Get alerts when specific phrases are sent in DMs 2.3.1

• Update support URL
• Fix phrasing for direct messages in approval queue
• Fix possible SQL error when applying visibility checks

There was a bug causing a server error when admin deleting conversations

Compatible fix for Conversation Essentials v2.5.0

• Require php 7.0+
• Require XenForo 2.1+
• Support XF2.2+

Fixed error creating new monitor with an associated user