Allow passing React elements to certain props

I noticed that the message prop on <Input /> only accepts a string. I’m sure there are other places where this is the case as well. I think it would be much more flexible if these instances could take React elements as well as strings.

Would you be in favor of easing up the PropTypes checks to allow passing React elements to these props?

This is important in particular for react-intl, where the idiomatic way of using translated messages is via the <FormattedMessage /> component:

<Input
  type='text'
  message={
    <FormattedMessage
      id='error'
      defaultMessage={`Whoops, that's an error.`}
      />
  }
  />

It can also be used for composing styles:

<Input
  type='text'
  message={
    <strong>
      This field is required.
    </strong>
  }
  />

In fact, both of these use-cases work currently, but React complains about the PropTypes checks in development.

[jxnblk]

The API has significantly changed in v1, where this shouldn’t be an issue anymore

[maxdeviant]

@jxnblk v1 looks great, btw 🎉