Save all shipping quotes that are calculated, rather than just the last
It also means that if the last shipping method checked didn't return any quotes, but earlier methods did return methods, shipping quotes would be available to the shopper
Save all shipping quote calculations rather than just the last one
This also means that if the last calculation did not give quotes the empty results don't overwrite previously calculated quotes
Merge branch 'pr-fix-shipping-method-calc' into branch-3.8.14.1-dev-merged

Conflicts:
	wpsc-includes/shopping_cart_functions.php