[RFC|Implemented] user_delete hook

[nickvergessen]

Name: hook_user_delete
Rationale: To revert things from viewtopic.php?f=111&t=33732
Placement: includes/functions_user.php at the end
Input arguments: $mode, $user_id, $post_username, $user_row
Output format: void

[gn#36]

The same thing goes for deleting topics, forums and posts since mods may need to delete data along with it.

It may be sensible to also be able to cancel a deletion process as well, sometimes the user may only be deleted if certain circumstances are met (for example the user may have to pay his debts first and the mod is used to remind the admin of this fact, or the mod may need to remind the admin that he is trying to delete some special user that cannot be deleted, e.g. a bot user or alike). Thus a hook should be called before (for cancellation) and after deletion (for cleanup), and maybe for altering the confirmation message as well.

[MichaelC]

Already implemented