[mythtv] Behaviour when entering LiveTV with a single tuner that is in use

[Robin Neatherway]

> It's been a long while sense I've even hit the live tv by accident, so
> my mistake :)

Yeah, I had a few reasons why I thought not many people would have
even thought about this:

1) People that run SVN head are unlikely to use Live TV
2) People that run SVN head are unlikely to have 1 tuner
3) People that run SVN head are unlikely to get confused about what is going on.

In my case this is to help my semi-ignorant flatmates not get confused
as to what is going on when they go into Live TV and it appears to
behave exactly as normal except that you then cannot change channel
etc. Cue cries of "the myth box is broken!". This also seems, to me,
to be more consistent.

Cheers,
Robin