[mythtv] channel table auto-population

[Torbjörn Jansson]

>> 
>> Don't delete the channels, mark them as invisibel instead.
>> 
> The problem I have with just setting these channels to
> invisible is that
> just browsing through the channels using the up and down
> arrows on live TV
> will go through these invisible channels as well

Works for me, i have invisible channels that don't show up when using livetv
browse mode.