Fix Squizmap #3584: "Anchor links in preview mode don't scroll the user".
Previous commits to fix hashlinks meant that they in fact indeed worked, but Firefox
did not scroll it because it limited the target of scrolling to the immediate iframe,
and that is already fully stretched by EES. (IE and Chrome worked fine.)
Add a click event for hrefs starting with "#" so that if the doc anchor exists, it
will use scrollIntoView() to move the frame and parent window, which works even in
Firefox.