Added withStateUpdaters as more flexible replacement for withStateHandlers …

[ElvenMonky]

Added third parameter to withStateHandlers to allow better control over event handling (persistance and propagation) and over result passed to setState (either object or function). Second parameter left for backwards compatibility and can be set to null/undefined.

[ElvenMonky]

With respect to proposal to change order of calls in issue #602

[istarkov]

Lets make a new hoc, withStateUpdaters, + help, + tests, +flow types, +flow test

[ElvenMonky]

Ok, seems done now. Sorry for the delay.

One thing to note: pushing from Windows didn't work. Had to fix it too