0.1.2.0

• switch SM :: s -> (SMState s a b) -> SM a b to SM :: (SMState s a b) -> s -> SM a b.
• the ArrowApp instance
• new functions: foldlSM, foldlDelaySM, delaySM, concatSM.
• working on Event, several undefined functions about Event.
• It's always hard to pick a name! 'Event', 'Evnt', 'Ev' or 'E'?