Combo patch for uc_donate

UC Donate is quite broken (in terms of adding donation products in the checkout pane). I needed to apply patches from #746004: uc_donate module contains D5 code - checkout pane fails to work, #943020: clicking back button on order review page results in 0.00 in donation checkout pane, #942868: donation added on checkout page doesn't appear on review page and #622506: On attribute selection (sub)total is not updated anywhere to get it to work (thanks @stella). The attached patch combines each of the respective patches for convenience.