throw error when setState's arguments are bad
better error message for mergeHelpers and setState
Don't store mount image on component instance
CSS widows property is unitless

Ref #836
More unitless CSS properties

volume, stress, pitch-range, richness
Refactor unit test
Unitless CSS flex properties
CSS column-count property is unitless
Remove unnecessary 'NA'-fallback for getTextContentAccessor()
Fix lines longer than 80 chars
throw when using component/component class as mixin

throw invariant error to help people new to mixins, so that they don't get misled into trying to mixin components into another component
Introduce PropTypes.shape

This diff introduces PropType.shape which lets you type an object. PropType.object was already defined and since it isn't a function I couldn't really overload the meaning to also accept a type list. Instead of doing hackery, I decided to name it `shape`.

An example where this could be used is style:

```
  propTypes: {
    style: PropTypes.shape({
      color: PropStyle.string,
      fontSize: PropTypes.number
    })
  }
```
Add `topContextMenu` to the event dependencies for `SelectEventPlugin`
Adding 'scope' to list of standard html attributes in react

scope is used for screen readers, so it would be nice to have. Documentation here: http://www.w3.org/TR/WCAG20-TECHS/H63
Kill last remaining use of `$` in React

It's only used here, so let's just inline this and get rid of the additional module.
Also it will make people like this guy happy: https://github.com/facebook/react/issues/900

(of course he might be even more happy if he wasn't using MS TFS....but that's a much bigger diff, and not one I can write...)
Document isMounted

Text from @petehunt
Fix copying files to build/npm-react recursively

The intention of the `npm-react/**/*` rule was to copy recursively but it would have flattened any nested directory structure. I changed the `build/modules` rule to copy recursively as well, which is necessary for `ReactTestUtils` to be able to require `test/mock-modules.js` successfully. (`ReactTestUtils` isn't included in a clean `npm-react` build currently but it will be in the future.)

This also makes running ART tests more practical.
Remove unused grunt jsx config options

Since 5466d0a06382892106da7e237f3330b43a60cc95, the `__DEV__` isn't used any more. I can't find anything that uses the `debug` flag either.
Fix double-binding to submit event

Fixes #916.
Clarify componentWillMount behavior