[mythtv] [PATCH] use presets instead of channums

[Edward Wildgoose]

> Maybe somebody is willing to think about a more decent implementation. I
> think a lot of european users will be very happy if they could use presets
> to change the channel.

Yep, we only get 5 decent channels over here, (perhaps up to 10-15 digital tv and I include the music channels as "decent".)  

This would be great to have included!