[mythtv] Ticket #1682: cleanup subtitles on channel change

[Pekka Jääskeläinen]

>  This patch will clear the subtitles on any resolution or aspect ratio
>  change, not just on channel changes. Can you try to make this more
>  specific to channel changes? I'm not sure this will even clear the
>  subtitles when the resolution and aspect ratio don't change on a channel
>  change.

Yes, you're probably right, now that I look into it. Is there a function
in NuppelVideoPlayer that gets called on channel changes only?

--
--PJ