player: erase frame buffer when another video is loaded

[Trek Hopton]

If a video is loaded while another is playing, the one that is playing needs to stop and then have its frame buffer erased. Currently the playing video will clash with the new one and you may see frames from both videos.

[Trek Hopton]

Resolved in PR #75 indirectly. A new frame buffer is used so the old one will be garbage collected.