Map fields based on another mapping object. Map fields from array to pascal case.

Currently if you have a class that inherits from another class you need to (re)specify all of the base classes fields in the child class. I added a method that takes another EKObjectMapping object and adds it's mapping  to the current mapping object.

The second method is a convenience method for working with JSON sources who use the pascal case naming convention (of course the mapFieldsFromDictionary method can be used but its a bit tedious when the only difference is the case of the first letter).