LiquidThreads code quality, bug fixes and cleanup:

LiquidThreads code quality, bug fixes and cleanup:
* Remove large swathes of dead code, hooks that have never existed, and dormant methods.
* Remove the TalkpageArchiveView, which has been inaccessible from the UI for ages.
* Break most miscellaneous hooks out into their own file, classes/Hooks.php
* Float the reply link on the RHS.
* Organise the hooks section of LiquidThreads.php somewhat.
* Remove deprecated =& syntax in some places.
* Move scratchTitle and related methods into Threads class instead of View class.
* Kill home-grown revision insertion code from leaveTrace, and rewrite it to use Article::doEdit
* Internal documentation, variable naming as appropriate.
* Remove special-case handling for links, unnecessary now.
* Fix customizeOldChangesList, it looks like it was never properly tested. Even if it had worked, it would have put (not by the author) on every edit to a post.
* Fail fast when trying to move a non-toplevel thread.
* Add rollback, extra links to the end of new-thread recentchanges entries.