Added Semigroup and Monoid instances to Moment and MomentIO. #223

Add @> operator. #229

switchE now takes an initial event. This is breaking change. The previous behavior can be restored by using switchE never. #165

Triggering an AddHandler no longer allocates, leading to a minor performance improvement. #237

A new once combinator has been added that filters an Event so it only fires once. #239

MonadMoment instances have been added for all possibly monad transformers (from the transformers library). #248

Some internal refactoring to reduce allocations and improve performance. #238

The Reactive.Banana.Prim hierarchy has been changed to better reflect the abstraction hierarchy. #241