Erply API version 1.5.15, 1.5.16

New feature: "Promotion stacking" added to API calculateShoppingCart. Promotion stacking means that the same item can trigger multiple promotions. For that to work, both promotions which are meant to be combined that way must be marked as "stacking". The check box for that,
"☑ Allow the same items to trigger other promotions after this promotion has been applied"
was added to promotion card in back office version 4.3.24+.
Promotions: combination "Get discount on multiple or unlimited items in exchange for reward points" is now supported, too.
Fixed: API saveConfParameter did not allow to edit parameter "branding".