OnColorSelectionListener as SAM

[ligi]

thanks for the library - really like it! I just find the OnColorSelectionListener a bit clumsy to use from Kotlin as you cannot just pass a lambda. What do you think converting it to a SAM so we can use it this way and have nicer code?
My suggestion would be to combine onColorSelected onColorSelectionStart onColorSelectionEnd and differentiate via a parameter (e.g. an enum SELECTED,START,END)
I could also provide this as a PR - but wanted your opinion first as it is a breaking change.

[thsaravana]

@ligi Could you show a usage of this interface for a client who's overriding all the 3 methods in the interface? We want to see how it would look like at the client code.

[ligi]

It would then just be a when/switch depending on the parameter inside