External tuner support for M3U

[mlcarson 13]

Support IPTV Video capture cards as part of the IPTV support by allowing for the selection of an executable for channel tuning.  Each time a channel change is requested, call the executable with a parameter for the channel number.  The executable would communicate with a device like an Itach Global Cahe to send an IR code to change the channel of the source being captured.  Everything else would be the same as the M3U tuner.   This could simply be added as an option for the existing M3U tuner.