Add a renderOption prop on SegmentedControls

[laserpants]

I wanted to add icons to my SegmentedControls buttons. I am not sure if there is a reason why only Text buttons are allowed but this pull requests introduces a renderOption prop which will allow an implementation to do something like:

  <SegmentedControls
    options         = {modes}
    onSelection     = {this.setMode.bind(this)}
    selectedOption  = {this.state.mode}
    renderOption    = {(option, selected) => {
      return (
        // ...render stuff
      )
    }}
  />

I made it so that if renderOption is not present, the default implementation is used:

  {'function' === typeof this.props.renderOption ? this.props.renderOption.bind(this)(option, selected) : (
    <Text style={style}>{label}</Text>
  )}

[ArnaudRinquin]

That's a good option. Thanks 👍

[ArnaudRinquin]

FYI I adjusted your code to use call instead of bind (see)

[laserpants]

Great! Thanks for the merge.

[ArnaudRinquin]

Feature published on npm with version 0.7.0 (also adds props documentation)