Added method Struct.sizeOf(Struct<?>) to determine the size of an already initialized struct object.
This is useful for generic methods where no explicit struct type is determined.
NSData uses this method now for initializing a new NSData object that wraps a struct.
It's also possible to get back the struct object of an NSData object, if the type is known.
Updated CoreFoundation dictionary types. CFMutableArray exposes methods to alter the items of the array now.