Remove huge switch statement and add Applier() interface instead.

[superchalupa]

Make it easier to add future extensibility by removing the big case statement in favor of an Applier() interface.

Signed-off-by: Michael Brown [email protected]

[jen20]

This is not a bad alternative approach - though personally I prefer the more functional style which results from a switch statement centralising the fold logic in one place. I'll update the post to reference this though! Thanks for the pull request!