ISR: AutoFit PGS and DVB subtitles.

- Preserve aspect ratio of subtitle frame
- Allow subtitle frame to go out of a video frame when their size mismatch
  in order to correctly display subtitles when video frame was cropped.
Add hidden option to crop HDMV subtitles when their size doesn't match video frame size.
ISR: Fix luminance output range for PGS and DVB subtitles.
DVB: Don't update stats when channel is not active.
DVB: Show current event time in the status bar
DVB: Make use out of the DVBState struct.
Mpeg2SectionData: Minor refactioring of the ParseEIT() method
DVB: Cosmetic for SetChannel()
Cosmetics for timers.
Cosmetics for stats.
DVB: Fix time calculations

StartTime was day off in certain cases.
DVB: Add channel name to snapshot filename