[mythtvnz] TV3 => Three

[Stephen Worthington]

It looks as though TV3 have rebranded themselves some time last week,
and are now known as Three.  So the EPG for them has stopped working,
and there is none on my MythTV boxes after Monday.  This also affects
TV3 PLUS1 which has become ThreePlus1.  Should we change the xmltv IDs
for these channels, or just map the EPG data from the new name to the
old xmltv IDs?