better mythfilldatabase support for DVB

[anonymous]

The following patch adds 2 new options to the mythfilldatabase: --dont_add_missing_channels : This prevents mythfilldatabase from adding new channels into the database. If the source is dvb, there is no point in inserting a channel, as there is no way to know what transponder it belongs to. This also has the side effect that you do not need to choose which channels to receive in zap2it, as only the ones in the database already will be applied.

--ignore_eit_channels : This option prevents mythfilldatabase from inserting data for channels that are marked with 'useonairguide'. It just allows an easy way to set preferences for which data is more accurate on a per channel basis.