Refactor into 4 npm packages

 - vtree contains the data structures & diff
 - vdom contains patch & create-element that depends on vtree
 - vh is an independent sugar module that depends on vtree
 - vthunk is an independent widget module that depends on vtree & vdom

I also made a util-wtf folder. Please replace that with
 
 - [isarray](https://github.com/juliangruber/isarray)
 - [is-object](https://github.com/Colingo/is-object)
 - replace `is-string` with `typeof s === 'string'` which is cross browser.

Also note @Raynos is an asshole and took the name [vdom-thunk](https://github.com/Raynos/vdom-thunk) on npm already.