[mythtv] [Experimental Patch] HDTV Captions

[Daniel Thor Kristjansson]

This is very preliminary, but I've written a basic EIA-708 caption 
decoder. It calls stub methods in a new EIA-708 Caption OSDType class.
Right now it just prints the caption command name, or the text in the 
case of a TextWrite Command.

   http://www.mrl.nyu.edu/~danielk/mythtv/hdtv-captions-v1.tbz

I think I may be assembling the packets incorrectly as the subtitle text 
just looks like gibberish, but it may just be that my test streams don't 
contain good captions.

-- Daniel