[For 1.8] MyConversations: a conversation plugin for MyBB

[Laird]

MyConversations version 1.2.2 has just been released.

New feature and fixes:

• Adds support for the new attachment user interface of MyBB 1.8.27.
  
• Bugfix: SQL error on searching solely by participant (from the quick-search field of the main conversation listing).
  
• Bugfix: Two settings on registration were by default unchecked when they ought to have been checked: "Allow other members to add me to conversations and conversation groups, including by starting new ones with me." and "Notify me by email when somebody starts a conversation with me."
  
• Bugfix: Zero was not being interpreted as unlimited for the per-usergroup setting "Maximum Participants Per Conversation/Group" for a member who belonged to other usergroups with a non-zero value for the same setting.