player: mention subtitles in av_desync_help_text

Insane .ass subtitle scripts can cause severe slowdown (depending on the
speed of the machine, or the insanity of the script), so mention how to
test without subtitles. This is mainly to make the user aware that
subtitle rendering can be a problem. For longwinded explanation, there
isn't enough space.
player: don't block terminal OSD while seeking

Seeking usually show the status on OSD. In terminal OSD mode, no status
is shown, because there is already a separate status line.
Unfortunately, the mechanism for showing the status was still active,
which forced showing no message while the code for showing seek status
was active.
player: redo terminal OSD and status line handling

The terminal OSD code includes the handling of the terminal status line,
showing player OSD messages on the terminal, and showing subtitles on
terminal (the latter two only if there is no video window, or if
terminal OSD is forced).

This didn't handle some corner cases correctly. For example, showing an
OSD message on the terminal always cleared the previous line, even if
the line was an important message (or even just the command prompt, if
most other messages were silenced).

Attempt to handle this correctly by keeping track of how many lines the
terminal OSD currently consists of. Since there could be race conditions
with other messages being printed, implement this in msg.c. Now msg.c
expects that MSGL_STATUS messages rewrite the status line, so the caller
is forced to use a single mp_msg() call to set the status line.

Instead of littering print_status() all over the place, update the
status only once per playloop iteration in update_osd_msg(). In audio-
only mode, the status line might now be a little bit off, but it's
perhaps ok.

Print the status line only if it has changed, or if another message was
printed. This might help with extremely slow terminals, although in
audio+video mode, it'll still be updated very often (A-V sync display
changes on every frame).

Instead of hardcoding the terminal sequences, use
terminfo/termcap to get the sequences. Remove the --term-osd-esc option,
which allowed to override the hardcoded escapes - it's useless now.

The fallback for terminals with no escape sequences for moving the
cursor and clearing a line is removed. This somewhat breaks status line
display on these terminals, including the MS Windows console: instead of
querying the terminal size and clearing the line manually by padding the
output with spaces, the line is simply not cleared. I don't expect this
to be a problem on UNIX, and on MS Windows we could emulate escape
sequences. Note that terminal OSD (other than the status line) was
broken anyway on these terminals.

In osd.c, the function get_term_width() is not used anymore, so remove
it. To remind us that the MS Windows console apparently adds a line
break when writint the last column, adjust screen_width in terminal-
win.c accordingly.
manpage: document --term-osd=force

Apparently this was forgotten when it was first added, or maybe it's an
arrifact from the rst conversion.
terminal-unix: add termcap/terminfo documentation links

Apparently, some people are not clever enough to google this
information.

Proper googling to find these links done by Kovensky.
terminal-unix: fix fallbacks in case terminfo/termcap are disabled

These two escape sequences were swapped. (They are used only if
terminfo/termcap are not available.)
terminal-unix: add fallback for enter key

This worked just fine if terminfo or termcap was available.
msg: fix printing of module header

The code to set root->header was moved before the point where it's used,
which broke the logic.
terminal-unix: fix terminfo/termcap name for cursor up

"ku" is for input, not output. This happened to work on urxvt, but broke
on xterm (and probably a dozen of other terminals).
msg: don't clear term OSD lines that are not used
demux_mkv: avoid skipping too much data in corrupted files

Until now, corrupted files were detected if the size of an element (that
should be skipped) was larger than the remaining file. This still could
skip larger regions of the file itself if the broken size happened to be
within the file.

Change it so that it's never allowed to skip outside the parent's
element.
demux_mkv: improve robustness by explicitly checking for level 1 elements

Matroska makes it pretty hard to resync correctly on broken files:
random data returns "valid" EBML IDs with a high probability, and when
trying to skip them it's likely that you skip a random amount of data
(instead of considering the element length invalid).

Improve upon this by skipping known level 1 elements only. Consider
everything else invalid and call the resync code. This might result in
annoying behavior when Matroska adds new level 1 elements, although it
won't be particularly harmful. Matroska doesn't really allow us to do
better (even mkvtoolnix explicitly checks for known level 1 elements).

Since we now don't always want to combine EBML element skipping and
resyncing, remove ebml_read_skip_or_resync_cluster(), and make
ebml_read_skip() more tolerant against skipping broken elements.

Also, don't resync when reading sub-elements, and instead do resyncing
when reading them results in an error.
demux_mkv: remove unused macros
ebml: remove unused functions

These were mostly replaced by ebml_read_element().
ebml: remove length parameters from read functions

Many ebml_read_* functions have a length int pointer parameter, which
returns the number of bytes skipped. Nothing actually needed this
(anymore), and code using it was rather hard to understand, so get rid
of them.
cocoa: add application icon to the Dock when run from CLI

Application icon was added to the Dock only when run inside of a bundle. That
was handled automatically by OS X using the Info.plist definition.

To add the Application icon when run as a CLI program, I used the samme
approach in the X11 code and loaded the icon as a static binary blob inside
of mpv's binary. This is the simplest approach as it avoid headackes when
relocating the binary and such.
player: avoid stalling when starting a network stream

Starting a network stream could stall by executing uncacheable stream
control requests (STREAM_CTRL_GET_LANG and STREAM_CTRL_GET_DVD_INFO).
Being uncacheable means the player has to wait until the cache is done
reading the current block of data. These requests can't be cached
because they're too complicated, so the only way to avoid them is
special casing the DVD and Bluray streams (which are the only things
which need these requests), and not doing them in other cases.

(This is kind of inelegant, but so is the rest of the DVD/BD code.)
player: don't print status in --idle mode

Apparently this annoys certain users. Restores old behavior.
Detect Lua on FreeBSD
w32_common: prevent decoding certain keys twice

This is a bit of a hack, but in order to prevent TranslateMessage from
seeing WM_KEYDOWN messages that we already know how to decode, move the
decoding logic to the event loop. This should fix #476, since it stops
the generation of extraneous WM_CHAR messages that were triggering more
than one action on keydown.