internal filters: enable avisynth support
PGS Subtitles: Fix a crash in some cases.

Mimic the change for DVB subtitles just for consistency.
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.
DVB: Add only supported services.
DVB: Add context menu to the navigation dialog.

Use std::vector to store channel in order to get better sort abilities.