Fix double-binding to submit event

Fixes #916.
Support two-way binding for checkboxes in LinkedValueMixin via 'checkedLink' property
Add invariant if both checkedLink and valueLink are provided
Fix typo in ReactDOMInput-test
Fix comparison in _handleLinkedCheckChange
Use Simulate.click instead of Simulate.input for simulating input on
checkbox.
replace "comments.json" with this.props.url
Fix references to the old ReactID syntax
Refactor Transaction to not rethrow errors

Rethrowing errors makes debugging harder. This makes it so that an exception in a render method can be caught using the purple stop sign (or the blue one, of course) in Chrome.
remove references to react-page
Fix docs typo
Merge pull request #880 from jbaiter/reactlink_checkbox

Support two-way binding for checkboxes in LinkedValueMixin via 'checkedLink' property
Update 09.2-form-input-binding-sugar.md
Fix animation example code

key should never be index into an array or there are bugs. Especially in
transitions.

Fixes #853
Use querySelectorAll instead of getElementsByName in ReactDOMInput.

We've been able to use `querySelectorAll` in all the browsers that we
support for some time now, but we haven't been able to test code that uses
it in the older version of `jsdom` that we were using, until recently.

Besides the general goal of modernizing our code, the impetus for this
specific change is that I'm trying to support testing without having to
render nodes into an actual document. The `.getElementsByName` method is
only defined on `document` and only works if the nodes you care about are
contained by the document.

On the other hand, `querySelectorAll` works on any DOM node, and allows a
more precise selection of just the `<input type="radio">` elements that
have the appropriate name.

IE8's implementation of `querySelectorAll` supports attribute-based
selectors, which is all we need here.
Warn for numeric object properties

Numeric keys will be ordered sequentially in Chrome/Firefox.

Warn the user if such keys are set on a child.
fix grammar mistake
Merge pull request #995 from Contra/patch-1

fix grammar mistake (reconciliation docs)
Merge pull request #985 from petehunt/remove-react-page

Remove references to react-page
Support `children` and `ref` for `cloneWithProps()`

We're not handling these correctly.