Support HEVC (UHD) Channels

I did some rough and basic changes to test with the HEVC Video Channels.

The stream worked for me, (no VLC, no mplayer, but ffplay from current ffmpeg-snapshot did show HEVC!), so I would like to make this change permanent with mumudvb.

(my first real pull request to mumudvb, yeah)

FYI: I tested with currently available SES Test streams on Astra 19.2E 10994MHz