Add PictureInPicture hotkey Option

[TurtleKingCode]

I noticed in your ReadMe page and source code that you didn't have a Picture-In-Picture option.
And I'm a sucker for that accessibility.
In my program, I was sort of able to make one for myself...

customKeys: {
      smallPlayer: {
        key: function(event) {
          return (event.which === 73);
        },
        handler: function(player, options, event) {
          if (player.isInPictureInPicture()) {
            player.exitPictureInPicture();
          } else {
            player.requestPictureInPicture();
          }
        }
      }
    }

I was hoping that you could add a PictureInPicture option in your library to make life easier for those like me.

[damanV5]

@ctd1500 Let me know , I can raise a PR for this.