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.
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.
Use GetLoadState() method instead of checking m_eMediaLoadState directly.
DVB: Fix time calculations

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