LowerUpperSwitch example, demonstrating switchB

[DevJac]

This is an example I wrote to help myself understand switchB. An example like this would have helped me when I was learning (I'm having some trouble installing wx, so I found the command line examples especially useful).

If you want me to make any improvements before merging, let me know. Perhaps making it interactive like the other command line examples would be worthwhile?

[DavidEichmann]

Just a note: you can write:

lowerEvent = const toLowerBehavior <$> filterE ("lower" `isPrefixOf`) fireEvent

as

lowerEvent = toLowerBehavior <$ filterE ("lower" `isPrefixOf`) fireEvent

in general

const x <$> y == x <$ y