Do not re create dispatch on every call.

[amsterdamharu]

Dispatch has a different reference every time you call createDispatch.
That is not how React.useReducer works and this should have consistant behavior.

Reference to issiue: #4

[ahungrynoob]

@amsterdamharu you can use https://github.com/ahungrynoob/use-root-reducer

[Tsourdox]

Why not just use the useRef hook to solve this? This PR seems overly complicated to me, maybe I'm missing something.

const { current: dispatch } = useRef(action =>
    Object.keys(combinedReducers)		
       .map(key => combinedReducers[key][1])		
       .forEach(fn => fn(action));
);