Simplify the way applications can get notifications when an effect finishes.
Now, instead of the 'DistortedEffects.(de)registerForNotifications()' 2 APIs, we call a single 'Effect.notifyWhenFinished()'.
Correct the EffectMessageSender.
Correct the Legal notice.
Rename all the classes that are not exported to application to 'Internal'
Move EffectMessageSender to the 'message' package (duh!)