Change from enums to normal classes

[dims12]

Why did you put all static methods to enums? This disallows to extend them! Suggest to turn enums to normal classes so that anybody can extend them.

[mikebaum]

@dims12 This was a pattern that was established before I joined the project. I guess the rational was to prevent people from instantiating the utils classes. I'm curious which classes you would like to extend and why? If you would like to add new methods, perhaps they could be added to the library in the classes you'd like to extend directly.

[dims12]

I was wishing to add observables for JList, which are apparently absent . Also there is a library, called Piccolo2D, which is closely related to Swing, but separate. It is not reasonable to add methods for this library into RxSwing, but in some application programmer may decide to extend SwingObservable to supply missing methods.