Fixes for r88113 and some realted changes:
* Modified <s>Article::editUpdates()</s> WikiPage::doEditUpdates() arguments to take a Revision object, an User object and options (much more readable that those boolean parameters)
* Call isCountable() on the old content and pass it to WikiPage::doEditUpdates() with the 'oldcountable' option so that it really reflects the old state of the page
* Updated all calls (no one in extensions) and removed the wrapper WikiPage::editUpdates()
* Call onArticleEdit() and onArticleCreate() (the one that is of course) from doEditUpdates()
* Removed $wgTitle hack from Import.php