Plugin Conversation Essentials 2.4.7

• Require Require XF2.1+
• Fix Conversation Improvements link is to the XF1 version instead of the XF2
• Reduce N+1 query behaviour on viewing a conversation
• Improve copy to conversation to thread progress tracking handling.

• Respect prefix value when using inline mod copy-to-thread option
• Setup to allow Multi Prefix to correctly extend copy-to-thread feature
  • Requires MultiPrefix v2.5.1 for full multi-prefix support

• Fix 'prefix' checkbox layout bug with XF2.1

• Cleanup some phrases references to XF1 'filtered' tab rather than the XF2 'conversation labels/rules'