Options for dvdbreakpoints
extractaudio: FLAC conversion

16-bit only for now.
Correct a comment in lsdvd
Fix bitreader
Fix ac3 header printing

Amazingly, neither clang or gcc caught this bug.
extractaudio: PCM repacking.
ac3strip: New tool (in progress).
ac3strip: More stuff.
ac3strip: More pieces.
ac3strip: More progress.

- Read auxiliary bits.

- Squash some warnings.

- Start moving fields into a context struct.

- General cleanup.
ac3strip: Replace all uses of copyint.

Now that we have a context struct, and the context struct has the
bitreader and bitwriter, we don't have to pass them around explicitly
any more. This makes the copy calls a bit cleaner, which is good because
there are a lot of them.

Also drop the "int" suffix because it seems slightly inaccurate.
Remove a trailing space.
extractaudio: Accept a range of chapters to rip.
extractaudio: Refactor file handling.

Introduce a writer type so we can layer writers on top of each other
(which the open_repack now does instead of forking). We can also do proper
cleanup on close now (open_flac no longer leaves zombie processes in its
wake).