cocoa: fix opening quarantined files on 10.9 with the bundle [2]

Fixup commit for bbc146927
wayland: fix fullscreen transparent border regions

The default behavior of weston changed some time ago to not fill the surface
black for fullscreen windows.

Now let mpv draw the whole screen in fullscreen mode.
wayland: better name for mouse coordinates

I had to look up what the surf_x and surf_y members do.
That means the name is not very good. Also a comment.
m_config: allow not allocating option struct, and use it

In cases we're just listing options or checking their values (as it
happens with -vo/-vf etc. suboption parsing), we don't need to allocate
abd initialize the actual option struct. All we're interested in is
the list of options.
m_config: remove unused fields

We don't need that anymore, because the old way to get default values
by recreating the m_config is gone.
m_config: slightly improve name handling
mplayer: make --length relative to actual start of file, instead of 0

We always use the file's timestamps, so the start time can be easily
something different from 0. Make the --length option respect this.
cocoa: constraint the window position a little more

The intention of this is to not make the window go outside the screen when
changing dimensions from 2x to .5x.
x11_common: reduce screensaver heartbeat from 30 to 10 seconds

Apparently this fixes issues with Gnome, which has a smaller timeout.
See github issue #315.
manpage: clarify --heartbeat-interval operation
README: add a link to the wiki about the FFmpeg vs. Libav issue
ao_alsa: don't include alloca.h

It's true that ALSA uses alloca() in some of its API functions, but
since this is hidden behind macros in the ALSA headers, we have no
reason to include alloca.h ourselves.

Might help with portability (FreeBSD).
options: don't let watch_later etc. overwite command line options

There are certain cases where mpv will automatically set options, such
as per-file configs, per protocol/VO/AO/extension profiles, and
watch_later resume configs. All these were overwriting the user's
options, even when they were specified on command line.

Add something that explicitly preserves command line options. This
means you can now actually use the command line to override any
options that the playback resume functionality backups and restores.

It still happily overrides options set at runtime (e.g. changed via
properties while playing a file; then playing the next file might
override them again), but maybe that's not a problem with typical use.
osc: make sure the OSC actually fits into the video
osc: add experimental seekbar tooltip

Not up to my quality standards (need ASS boundingboxes), so disabled by default and undocumented for now.

Can be enabled with seektooltip=yes in plugin_osc.conf
osc: fix bug for no-duration cases
osc: display cache status only below 45%

Turnes out, when playing stuff over WiFi, the cache may go below 48%
quite frequently.
docs: osc: update cache display percentage.
mpvcore: add a note about desync on track switches
af_volume: remove unused features

Roughly follows MPlayer svn commits 36492 and 36493. We also remove
the volume peak reporting. (There are much better libavfilter filters
for this, I think.)