mplayer: factor config dir creation

Move it into its own function.
command: alias video/audio/sub properties to -vid/-aid/-sid

Now vid/aid/sid can be used as properties. video/audio/sub still work,
but they are aliases for the "real" properties.

This guarantees that options/properties use the same value range. One
consequence is that the video/audio/sub properties return "no" as value
if no track is selected instead of -1.
core: add playback resume feature (manual/opt-in)

A "watch later" command is now mapped to Shift+Q. This quits the player
and stores the playback state in a config file in ~/.mpv/watch_later/.
When calling the player with the same file again, playback is resumed
at that time position.

It's also possible to make mpv save playback state always on quit with
the --save-position-on-quit option. Likewise, resuming can be disabled
with the --no-resume-playback option.

This also attempts to save some playback parameters, like fullscreen
state or track selection. This will unconditionally override config
settings and command line options (which is probably not what you would
expect, but in general nobody will really care about this). Some things
are not backed up, because that would cause various problems. Additional
subtitle files, video filters, etc. are not stored because that would be
too hard and fragile. Volume/mute state are not stored because it would
mess up if the system mixer is used, or if the system mixer was
readjusted in the meantime.

Basically, the tradeoff between perfect state restoration and
complexity/fragility makes it not worth to attempt to implement
it perfectly, even if the result is a little bit inconsistent.
stream: fix bad cache behavior introduced by recent commit

Commit 4d14a42, a seemingly harmless change, introduced very bad cache
behavior when the cache isn't forked, such as on Windows, where it uses
threads. Apparently the cache code was designed for forking, and an
unknown obscure condition causes severe performance degradation if a
STREAM_CTRL is sent to the cache on every frame.

Since the cache code is literally insane (uses shared memory + fork(),
and has hacks to make it work with threads, is messed into the stream
code in extra-hacky ways), we just fix it by caching the STREAM_CTRL in
question.

This is also done for some other STREAM_CTRLs that are called on each
frame, such as playback duration. This indicates that the cache code has
some inherent problem with answering such requests in a timely matter,
and that there's no easy way around this.

(Even if the cache is eventually rewritten, these things will probably
have to be cached, otherwise you'd have to forcibly block until the
stream implementation is done with a blocking read. The real question
is why it worked fine with the forked cache, though.)
subreader: fix one more unsafe sscanf call with "%["

"%[,.:]" conversion was used with a buffer that could be shorter than
the matched string. Suppress assignment of the conversion since the
value wasn't used anyway, and also limit match length to 1 as it
doesn't look like the intent was to match longer runs of the
characters.

Merged from mplayer2 commit 5cb9aac. Note that the other half of the
mplayer2 commit is already part of the mpv commit d98e61e. (I'm not
sure why. The mplayer2 commit date precedes mpv's, but was pushed long
after the mpv change was pushed; either one of the dates is wrong, or
we did the same work twice - in that case, thanks a lot...)
img_format: fix broken condition

This caused all formats with fewer than 8 bits per component marked as
little endian. (Normally, only some messed up packed RGB formats are
endian-specific in this case.)
vf_yadif: actually set PTS for output frames

The original frame PTS was used instead. Oops...
Fix some cppcheck / scan-build warnings

These were found by the cppcheck and scan-build static analyzers. Most
of these aren't interesting (the 2 previous commits fix some interesting
cases found by these analyzers), and they don't nearly fix all warnings.
(Most of the unfixed warnings are spam, things MPlayer never cared
about, or false positives.)
demux: remove retrieval of chapter end time

The frontend doesn't use this.

Also use double for returning the chapter times. Everything uses double
for times, and there's no reason to use float here.
stream: report chapter times, use time seeks for DVD chapters

Allow the stream layer to report chapter times. Extend stream_dvd to do
this. I'm not 100% sure whether the re-used code is bug-free (because it
was used for slave-mode and/or debugging only).

MAke the frontend do time-based seeks when switching DVD chapters. I'm
not sure if there's a real reason STREAM_CTRL_SEEK_TO_CHAPTER exists
(maybe/hopefully not), but we will see.

Note that querying chapter times in demuxer_chapter_time() with the new
STREAM_CTRL_GET_CHAPTER_TIME could be excessively slow, especially with
the cache enabled. The frontend likes to query chapter times very often.
Additionally, stream_dvd uses some sort of quadratic algorithm to list
times for all chapters. For this reason, we try to query all chapters on
start (after the demuxer is opened), and add the chapters to the demuxer
chapter list. demuxer_chapter_time() will get the time from that list,
instead of asking the stream layer over and over again.

This assumes stream_dvd knows the list of chapters at the start, and
also  that the list of chapters never changes during playback. This
seems to be true, and the only exception, switching DVD titles, is not
supported at runtime (and doesn't need to be supported).
demux: don't name unknown chapters "unknown"

The frontend's fallback for missing chapter names is better.
Merge branch 'master' into bluray_test2

Conflicts:
	stream/cache2.c