Add hidden prop to ReactPlayer

[kevinzwhuang]

Description:
hidden is a standard HTML prop of react. I was building a toggle feature to hide ReactPlayer -- as opposed to re-rendering the player each toggle, which would lag due to having to retrieve and re-embed the media each time -- and found that ReactPlayer does not accept a hidden prop to hide its top level div. In order to hide it using hidden, I had to write another parent div above ReactPlayer just to hide the component.

// Not the best way to hide a component
<div hidden={ myBoolean }>
  <ReactPlayer url={ this.props.randomURL }>
</div>

Changes Proposed:
I'd like to propose that hidden be added to one of the standard props ReactPlayer accepts (alongside the standard style & className props). Like so:

// Feels better this way!
<ReactPlayer
  url={ this.props.randomURL }
  hidden={ myBoolean }
/>

I've included working code that allows this very use case in this PR. I've also included a line to the Props documentation in README.md about hidden as a prop that can hide ReactPlayer.

[kevinzwhuang]

To verify full functionality that hidden works, you can try modifying the demo as such:

//src/demo/App.js
//...
//...
export default class App extends Component {
  componentDidMount() {
    var interval = setInterval(this.toggleHide, 1000); // Hide the player every 1000ms
  }
  toggleHide = () => this.setState({ hidden: !this.state.hidden }) // Toggle hidden state
//...
//...
  render () {
//...
//...
    return (
      <div className='app'>
        <section className='section'>
          <h1>ReactPlayer Demo</h1>
          <ReactPlayer
            ref='player'
            className='react-player'
            width={480}
            height={270}
            hidden={this.state.hidden} // Provide hidden state as a prop to ReactPlayer
//...
//...

[kevinzwhuang]

Thoughts on this, @cookpete?

[cookpete]

Yeah this looks good. I would normally have just used className or style to hide the player but I wasn't aware of the hidden attribute. Nice work!

As this is adding new functionality, I'll publish as a new minor version. Should probably look at moving to 1.0.0 soon.