Vega Strike Code

Finally, a GPL-licensed Sol system. It still needs a little tweaking on
orbital speeds.

Normalize volume for confed chatter and a couple of cockpit events that were a bit faint

Ability to specify gain for comms and cockpit event sounds, to more easily normalize volume across all content

Fix audio stream timestamp handling:
- use pts, as it's a more accurate timestamp for audio (since audio is a clock source)
- ignore AV_NOPTS_VALUE, as many incomplete packets contain no pts

Make video de-jitter skip less, hasten up more, and skip back only when really needed (it's expensive)

Fix compatibility with older ffmpeg

Fix segmentation fault in 32-bit OS when using --debug=3
(int64_t requires %lld format, %ld in 32-bit is 32-bit)

Fix audio streaming to make it not consider buffer-starved streams as finished

New confed chatter by maxaxle. Incomplete, though. Some friendly
messages are missing their entry in the xml, and some builtin messages
are entirely missing.

Better radializer. Much.