Store "Qty Sold" in separate field, not in "Hits" field and update processing code too

I propose to create "QtySold" for products and update it instead of "Hits" field. Then we should use Hits field for counting how much users are visiting product detail page (as it works for link detail page for now). Then we'll create new "top_seller" value for "types" parameter (usage: <inp2_PrintList render_as="top_seller_element" types="top_seller" parent_cat_id="any"/>) which will list only products, that were sold at all. Default sorting for such product list will be: most sold on top with user unable to change it of course.