vo_opengl: avoid texture arrays for compatibility with Intel low quality crap

Commit a0b43a1 changed textures to an array, because additional
per-texture information was needed and managing this as array is more
elegant. This broke playback on Windows with Intel drivers (window
shows green video, even though subtitles/OSD work correctly). So change
it back to make it work again.

Affected driver: Intel(R) HD Graphics 3000 9.17.10.2932
Merge branch 'master' into low_quality_intel_crap

Conflicts:
	video/out/gl_video_shaders.glsl
	video/out/vo_opengl.c
dither: don't use long double

This fixes compilation with broken libcs, like on Cygwin. C99
absolutely requires long double and associated functions like expl,
even if long double is double. But newlib (used by cygwin) omits
declaration for these if long double is equivalent to double.

The extra precision is not needed here, so remove it to make life
easier for the single person using mpv with cygwin.
configure: rename --enable/disable-libquvi to --enable/disable-libquvi4

--disable-libquvi creates the impression that it disables libquvi 0.9
as well. It doesn't, because it refers to libquvi 0.4, and 0.4 and 0.9
are practically completely different libraries. Make this more explicit
by renaming the switch to include the "4" version number.
ao_jack: increase buffer size, always round up buffer size

This should help with github issue #128, which reported stuttering
distorted sound with 6 channel audio, but not with 2 channels.
ao_jack: allow more control about channel layouts
core: make network options available even if old net code is disabled

Preparation for removing the old network code.
Remove internal network support

This commit removes the "old" networking code in favor of libavformat's
code.

The code was still used for mp_http, udp, ftp, cddb. http has been
mapped to libavformat's http support since approximately 6 months ago.
udp and ftp have support in ffmpeg (though ftp was added only last
month). cddb support is removed with this commit - it's probably not
important and rarely used if at all, so we don't care about it.
manpage: fix section headings
stream: re-add accidentally removed seek call

This was under CONFIG_NETWORKING, so in theory it should have been save
to remove. But actually this disables forward skipping when reading
from a pipe. (Still a questionable feature, because it doesn't behave
well with libavformat - but it was not supposed to be changed.)
stream: remove weird STREAMTYPE_STREAM special handling

This was an old leftover from an earlier cleanup (which happened in
2003), and which used "special" stuff for streams that could be only
forward-seeked.

Also, don't add mode flags to s->flags; they're supposed to be in
s->mode instead.
Remove some leftovers from network removal

stream_vstream.c in particular was actually dependent on the network
code, and didn't compile anymore.

Cleanup the protocol list in mpv.rst, and add some missing ones
supported by libavformat to stream_lavf.c.
stream: don't treat position 0 specially

Seeking to position 0 meant to try reconnecting with some streams,
actually just the internal http implementation. This has been removed,
so we don't need the special handling anymore.

This means we don't have to be stuck in a retry loop if the stream
doesn't even support reconnect.
configure: prune some more crap

All of the removed lines are hopefully useless and didn't do anything.
configure: simplify arch macros
osdep: remove unused mmap compatibility hacks

Not sure how this worked. Only af_export.c and tvi_v4l2.c were
using mmap, but they didn't include osdep/mmap.h or mmap_anon.h. In
any case, we trust that the target system is sufficiently POSIX
compliant if mmap is actually defined (as checked by configure).
stream: unbreak streams with large sector sizes (stream_cdda)

Commit 7b16d4b changed some stream implementations to check the buffer
size passed to them. This made stream_cdda stop working, because the
default buffer size is smaller than the CDIO frame size. So pass the
sector size instead of the (arbitrary) default buffer size.
Remove old demuxers

Delete demux_avi, demux_asf, demux_mpg, demux_ts. libavformat does
better than them (except in rare corner cases), and the demuxers have
a bad influence on the rest of the code. Often they don't output
proper packets, and require additional audio and video parsing. Most
work only in --no-correct-pts mode.

Remove them to facilitate further cleanups.
demux: remove audio parser

The audio parser was needed only by the "old" demuxers, and
demux_rawaudio. All other demuxers output already parsed packets.

demux_rawaudio is usually for raw audio, so using a parser with it
doesn't usually make sense. But you can also force it to read
compressed formats with fixed packet sizes, in which case the parser
would have been used. This use case is probably broken now, but you
will be able to do the same thing with libavformat demuxers.
demux: remove some old stream header functions