tv: unqueue buffers correctly (maybe, maybe not)

I clue no idea what I'm doing, but at least it doesn't hang anymore when
closing a tv:// stream using a v4l2 loopback device.
tv: remove duplicated crap

The logging functions already add a prefix. Original MPlayer devs must
have liked code duplication a lot.
stream: remove duplicate message
stream: fix --stream-dump dropping the file header

stream_rar.c peeks the first few bytes when trying to open, which means
that opening any stream reads at least 2KB of data (internal buffer
size) on opening. This broke --stream-dump, which saved only the data
following this initial buffer.

Hack it around by writing the current buffer to the capture file too,
and move stream_capture_write() above stream_set_capture_file() for this
purpose.

Cleaner solutions might include: handling the terrible rar thing
differently, or using the "proper" stream API for dumping. (The latter
is not done, because --stream-dump shares code with the --stream-capture
misfeature.)

Fixes #1215.
build: enable cdda:// by default again

Apparently people want this. (???)

See #1214.
lua: fix some more lua_tostring() mistakes

Why can't it just raise an error?
tv: reduce waiting loop from 10ms to 1ms

I can't believe how shitty this (MPlayer-derived) code is. Maybe it
should be fixed or be replaced with using libavdevice, but that doesn't
seem worth the effort.

Anyway, for now reduce the time it's blocking to wait for new frames
from 10ms to 1ms, because 10ms might be a bit too tight: it could
deliver the frame up to 10ms late - now it's only up to 1ms. (And yes,
it does that instead of using condition variables. It also abuses
volatile variables as atomics. It's hilarious.)
tv: remove some differences between immediate/normal mode

The immediate mode (which is the default) uses a tiny ringbuffer and
doesn't grab timestamps. This leads to quite bad behavior due to the
fact that there's an additional buffer between playloop and TV code (the
demuxer thread, which doesn't exist in MPlayer).

Always grab the timestamps and use a decently-sized buffer. I still have
no clue what I'm doing, and hacked it until it appeared to work. Report
regressions if you experience any.
manpage: use the proper environment variable for CSIDL_APPDATA
video: initial dxva2 support

Shamelessly stolen from ffmpeg. It probably doesn't work - you can debug
it yourself.