Fix category discussion counter
Ensure that discussion counter increments when a discussion is moved to a new category. Convert tabs to spaces and add braces to all control statements.
Conflicts:
	applications/vanilla/models/class.discussionmodel.php
Fix incorrect merge in DiscussionModel 3444e112fea0ad65c1d31cafb78025d697588df9
Merge pull request #2202 from vanilla/hotfix/category-update-counter

Fix category discussion counter on move