LiquidThreads updates:

LiquidThreads updates:
* Overhaul deletion system. Totally remove deletion special page, deletion will now be handled through the standard MediaWiki deletion system. When a thread's "root" is deleted, the thread itself is marked as deleted. When the page is re-undeleted, the thread will be marked as restored.
* Move some class files from Lqt* to simply *.
* Remove HistoryIterator class, pointless.
* Miscellaneous code quality as found.

Includes core changes to pass comment along with ArticleRevisionUndeleted hook.