make adding items to cart more flexible
make adding items to cart more flexible

allow updating an existing row that can be specified in overriden method

yacon/koala-framework,darimpulso/koala-framework,Sogl/koala-framework,kaufmo/koala-framework,fraxachun/koala-framework,koala-framework/koala-framework,Ben-Ho/koala-framework,yacon/koala-framework,Ben-Ho/koala-framework,kaufmo/koala-framework,koala-framework/koala-framework,nsams/koala-framework,yacon/koala-framework,kaufmo/koala-framework,darimpulso/koala-framework,fraxachun/koala-framework,nsams/koala-framework,nsams/koala-framework,Sogl/koala-framework