DVB Header information for video streams

Added header information from PMT tables for MPEG-2 and H.264 Streams. The switching channel approach had to be reviewed as well.
Minimized the number of windows size changes each time a channel is switched

Signed-off-by: xpc1000 <xavier_portell@hotmail.com>
Merge pull request #51 from xpc1000/master

DVB: Use the header information to improve the channel switching process.