VBResults - Thread Merge 1.0.7

Fix built-in thread merge indexing/SERP issue, subscription deletions, add merge notice.​

The built-in tool has 5 problems if you merge 'Thread B' into 'Thread A':

1. 'Thread B' will only redirect to the first page of 'Thread A'. If 'Thread A' already had a full page of posts, old links will go to a page without the expected content.
   
   This can lead to compounding problems with Google SERPs because the first post of the new thread no longer has the content that was expected and is deindexed.
   
   
2. If 2 or more users are already watching 'Thread B', then merging into 'Thread A' deletes their subscriptions which destroys user engagement.
   
   In a way, merging is literally a 'delete engagement' button.
   
   
3. There is no way for people replying to 'Thread B' previously to know a merge occurred unless a moderator makes a boilerplate reply saying the thread was merged.
   
   This is an extra step for the moderator to take.
   
   
4. The merged thread leaves a redirect entry taking up the space of a real one that has content, and the only way to avoid that is to not redirect.
   
   
5. If 1 or more users are reply banned from 'Thread B', then merging into 'Thread A' deletes those reply bans and can let trolls invade the target thread.

This add-on solves every problem automatically:

1. If post #1 of 'Thread B' is merged into page 3 of 'Thread A', the redirect always goes there instead
2. Watch subscriptions are transferred over to the new thread to retain engagement
3. A notice now indicates when a merge has taken place, see below
4. Merged thread redirect entries are now hidden from the thread list
5. Reply bans are now merged

Note: For merges that were previously done without this add-on, the Google deindexing is irreversible.

Disclosure: This add-on is fully functional and is receiving updates if/when it is broken by a core XF update only; there are otherwise no updates and there is no support.