JavaDoc fixes, most of them for WICKET-5410 (All IXyzSettings are
removed)
WICKET-5759 AjaxRequestAttributes extra parameters aren't properly handled in getCallbackFunction()
WICKET-5759 AjaxRequestAttributes extra parameters aren't properly handled in getCallbackFunction()

Fix test expectations
WICKET-5775 Replace the session upon successful signin for better support for Session Fixation