version.sh: fix git rev. generation (.git is not always a directory)

It appears git submodule handling recently changed, changing the .git
directory to a regular file containing submodule specific information.
This means that version.sh would generate "#define VERSION "git-UNKNOWN""
if the checkout is a submodule, because it explicitly checks for a .git
directory using test -d. Change it to -e so that this case is handled
correctly.
command: add command to show playlist on OSD
core: remove --edlout functionality

This could write .edl files in MPlayer's format. Support for playing
these files has been removed from mplayer2 quite a while ago. (mplayer2
can play its own, "new" .edl format, but does not support writing it.)

Since this is a rather obscure functionality, and it's not really clear
how it should behave (e.g. what should it do if a new file is played),
and wasn't all that great to begin with (what if you made a mistake?
the "edl_mark" command sucks for editing), get rid of it.

Suggestions how to reimplement this in a nicer way are welcome. If it's
just about retrieving timecodes, this in input.conf will do:

    KEY print_text "position: ${=time-pos}"
Remove BSD legacy TV/radio support (BT848 stuff)

FreeBSD actually supports V4L2, and V4L2 supports this chip. Also,
this chip is from 1997. Farewell.
ao_dsound: support 6.1 and 7.1 channel configurations

Instead of doing the channel reordering manually, use the existing
support in reorder_ch.c.

Untested.
mixer: prefer AO softvol control over volume filter

This partially reverts earlier decisions, when I thought it would
always be better to prefer the audio volume filter over the AO's,
because the AO's relies on the underlying audio-API, which could
be broken or exhibit unusual behavior (like it happened with ao_dsound).

However, since the audio buffer can be quite large (500 ms), and we
don't attempt to flush & refilter the audio on volume changes, always
prefer AO volume control (as long as the AO mixer doesn't control the
system mixer).

Also document what the mixer.c related AO fields mean (hopefully not
too brief).
audio/out: prefer ao_dsound over ao_portaudio

On Linux, ao_portaudio has weird freezing issues (possibly specific to
the ALSA backend, though). Also ao_dsound is more likely to get multi-
channel audio output right, and ao_portaudio probably mangles these.
video/out: change autoprobe order

Basically, move vo_opengl above the other VOs (except vo_vdpau). This
changes preferences on Windows and Linux.

Move vo_opengl_old further down and make it the last fallback (before
vo_x11).

vo_caca is crap (no pun intended), and should never be autoprobed.
audio/out, video/out: hide encoding VO/AO

mpv -ao help and mpv -vo help shouldn't show the encoding outputs (named
"lavc" on both cases). Also make it impossible to select these manually
when not encoding.
options: change handling of "no-" options

Normally, all flag options can be negated by prepending a "no-", for
example "--no-opt" becomes "--opt=no". Some flag options can't actually
be negated, so add a CONF_TYPE_STORE option type to disallow the "no-"
fallback.

Do the same for choice options. Remove the explicit "no-" prefixed
options, add "no" as choice.

Move the handling of automatic "no-" options from parser-mpcmd.c to
m_config.c, and use it in m_config_set_option/m_config_parse_option.
This makes these options available in the config file. It also
simplifies sub-option parsing, because it doesn't need to handle "no-"
anymore.
config: do not require option value

Now setting a value with "=" is not required anymore in config files.
This should work analogous to command line arguments. Putting an entry
"opt=value" into the config file is like "--opt=value" on the command
line, and "opt" is like "--opt=" and "--opt".
options: unify single dash and double dash options

There were two option syntax variations:

    "old":  -opt value
    "new": --opt=value

"-opt=value" was invalid, and "--opt value" meant "--opt=" followed by
a separate option "value" (i.e. interpreted as filename). There isn't
really any reason to do this. The "old" syntax used to be ambiguous
(you had to call the option parser to know whether the following
argument is an option value or a new option), but that has been removed.
Further, using "=" in the option string is always unambiguous.

Since the distinction between the two option variants is confusing,
just remove the difference and allow "--opt value" and "-opt=value".

To make this easier, do some other cleanups as well (e.g. avoid having
to do a manual lookup of the option just to check for M_OPT_PRE_PARSE,
which somehow ended up with finally getting rid of the m_config.mode
member).

Error reporting is still a mess, and we opt for reporting too many
rather than too few errors to the user.

There shouldn't be many user-visible changes. The --framedrop and
--term-osd options now always require parameters.

The --mute option is intentionally made ambiguous: it works like a flag
option, but a value can be passed to it explicitly ("--mute=auto"). If
the interpretation of the option is ambiguous (like "--mute auto"), the
second string is interpreted as separate option or filename. (Normal
flag options are actually ambiguous in this way too.)
cleanup: replace OPT_FLAG_ON and OPT_MAKE_FLAGS with OPT_FLAG

OPT_MAKE_FLAGS() used to emit two options (one with "no" prefixed),
but that has been long removed by special casing flag options in the
option parser. OPT_FLAG_ON() used to imply that there's no "no-"
prefixed option, but this hasn't been the case for a while either.
(Conceptually, it has been replaced by OPT_FLAG_STORE().)

Remove OPT_FLAG_OFF, which was unused.
mplayer: remove seconds/centiseconds display from terminal status line

Doesn't have much of a purpose for normal playback. You can get
milliseconds display with --osd-fractions. It's also possible to build
a custom status line with --status-msg.

This gives more space on the status line and, in my opinion, is a bit
less annoying.
Check return values of some mp_find_..._config_file function calls for NULL
options: change --no-config option, make it apply to input.conf as well

Simplify --no-config and make it a normal flag option, and doesn't take
an argument anymore. You can get the same behavior by using --no-config
and then --include to explicitly load a certain config file.

Make --no-config work for input.conf as well. Make it so that
--input:conf=file still works in this case. As a  technically unrelated
change, the file argument now works as one would expect, instead of
making it relatively to "~/.mpv/". This makes for simpler code and
easier to understand option semantics. We can also print better error
messages.
dec_audio: uncrustify
core: redo how codecs are mapped, remove codecs.conf

Use codec names instead of FourCCs to identify codecs. Rewrite how
codecs are selected and initialized. Now each decoder exports a list
of decoders (and the codec it supports) via add_decoders(). The order
matters, and the first decoder for a given decoder is preferred over
the other decoders. E.g. all ad_mpg123 decoders are preferred over
ad_lavc, because it comes first in the mpcodecs_ad_drivers array.
Likewise, decoders within ad_lavc that are enumerated first by
libavcodec (using av_codec_next()) are preferred. (This is actually
critical to select h264 software decoding by default instead of vdpau.
libavcodec and ffmpeg/avconv use the same method to select decoders by
default, so we hope this is sane.)

The codec names follow libavcodec's codec names as defined by
AVCodecDescriptor.name (see libavcodec/codec_desc.c). Some decoders
have names different from the canonical codec name. The AVCodecDescriptor
API is relatively new, so we need a compatibility layer for older
libavcodec versions for codec names that are referenced internally,
and which are different from the decoder name. (Add a configure check
for that, because checking versions is getting way too messy.)

demux/codec_tags.c is generated from the former codecs.conf (minus
"special" decoders like vdpau, and excluding the mappings that are the
same as the mappings libavformat's exported RIFF tables). It contains
all the mappings from FourCCs to codec name. This is needed for
demux_mkv, demux_mpg, demux_avi and demux_asf. demux_lavf will set the
codec as determined by libavformat, while the other demuxers have to do
this on their own, using the mp_set_audio/video_codec_from_tag()
functions. Note that the sh_audio/video->format members don't uniquely
identify the codec anymore, and sh->codec takes over this role.

Replace the --ac/--vc/--afm/--vfm with new --vd/--ad options, which
provide cover the functionality of the removed switched.

Note: there's no CODECS_FLAG_FLIP flag anymore. This means some obscure
container/video combinations (e.g. the sample Film_200_zygo_pro.mov)
are played flipped. ffplay/avplay doesn't handle this properly either,
so we don't care and blame ffmeg/libav instead.
demux_lavf: remove code duplication

Also move the lang field into the general stream header. (SH_COMMON is
an old hack to "share" code between audio/video/sub headers.)

There should be no functional changes, other than not printing stream
info in verbose mode or with slave mode. (The frontend already prints
stream info, and this is just a leftover when individual demuxers did
this, and slave mode remains broken.)
demux_lavf, ad_lavc, vd_lavc: refactor, cleanup

Rearrange some code to make it easier readable. Remove some dead code,
and stop printing AVI headers in demux_lavf. (These are not actual AVI
headers, just for internal use.)

There should be no functional changes, other than reducing output in
verbose mode.