[Feature Request] Make adding various materials to landscapes easier

As-is, its way too convoluted and way more complicated than it should be, having to make a whole separate material when I want to use a couple, and not being able to add already existing materials without jumping through many hoops. I honestly thought it was going to be as easy as adding different layers for materials like it is for grass/foliage painting. I would **love **if you could simplify it, so far its my only complaint with UE4