Simplify typed props

[johanandren]

Currently the typed Props is a List structure, where new elements for the same type of key wins but old elements are kept in the list, a bit like the stream attributes. When we construct the actor we search for the first element. Additionally there seems to be some methods that are not used at all or only used from tests (allOf, filterNot).

Every time I look at the typed props I have to spend a while to figure out how they work and why. Would it be simpler if it was just an internal immutable map with some key and an ugly typecast of the actual value instead, or some other built in datastructure for that part?