Make C4View a pure Swift class.

[Buza]

If we have no plans to leverage the runtime flexibility that being an Obj-C subclass provides, it might make sense to make C4View (and any other classes) pure Swift classes to leverage some of the method dispatch and size improvements.

[alejandro-isaza]

I agree, we used to have methods that used selectors to dispatch events but now that is all gone.

[alejandro-isaza]

Actually there are two things that use this: EventSource.swift for the on(..) methods and setValue(:forKey:) which I don't see being used. If we are ok to remove the event source stuff then we can do this @C4Framework?