mplayer: print a message when writing watch_later config for resume

Putting this into stable, because it might help debugging certain
issues, and also making the user aware what's happening.
README: update Contact info with Mailing Lists
README: add clarification about --enable
macosx: add webm the filetypes handled by the bundle
stream_dvd: prevent segmentation fault with some broken files

I have a sample where some final chapters are missing. This was causing a
segmentation fault when trying to fetch chapter times for them.

This makes the code ignore those chapters.
manpage: remove version and date fields

These would have to be updated manually all the time. Replacing them
automatically would be possible, but additional work, and would force
regeneration of the manpage way too often.

We decided that we don't need these fields.
manpage: remove bogus space in example usage
demux_mkv: don't add too many subtitle packets during seeking

In insane files with a very huge number of subtitle events, and if the
--demuxer-mkv-subtitle-preroll option is given, seeking can still
overflow the packet queue. Normally, the subtitle_preroll variable
specifies the maximum number of packets that can be added. But once this
number is reached, the normal seeking behavior is enabled, which will
add all subtitle packets with the right timestamps to the packet queue.
At this point the next video keyframe can still be quite far away, with
enough subtitle packets on the way to overflow the packet queue.

Fix this by always setting an upper limit of subtitle packets read
during seeking. This should provide additional robustness even if the
preroll option is not used.

This means that even with normal seeking, at most 500 subtitle packets
are demuxed. Packets after that are discarded.

One slightly questionable aspect of this commit is that subtitle_preroll
is never reset in audio-only mode, but that is probably ok.
mplayer: read subtitle packets as soon as possible

Call update_subtitles() on every iteration of the playloop, so that
subtitle packets are read as soon as possible, instead of every time a
video frame is displayed. This helps in case the packet queue is swamped
with subtitle packets, which can happen with certain insane mkv files.
The change will simply cause the subtitle queue to be emptied on each
playloop iteration.

The timestamps update_subtitles() uses for display are the same before
and after this commit. (Important for files which have subtitle packets
with timestamps or duration not set.)
path: fix undefined behavior

The homepath variable was static, and its value was set to a stack
buffer. This means a second invocation of the function would trigger
undefined behavior. Moreover the stack buffer always went out of scope
before homepath was used.
Config path functions can return NULL

It's quite unlikely, but functions like mp_find_user_config_file() can
return NULL, e.g. if $HOME is unset.

Fix all the code that didn't check for this correctly yet.
af_export: fix compilation warning

Blargh.
wayland/common: exit properly on fd errors

Before this commit there was just an error message, but the file descriptor was
still open. Now we close the file descriptor and prevent it from calling
endlessly. Also a CLOSE_WIN event is sent which closes the window eventually if
the action of CLOSE_WIN is set to quit or quit_watch_later.
x11_common: fix behavior if XCreateIC() fails

This consists of 3 commits squashed and cherry-picked from master
(there were some minor conflicts):

vo/x11_common: Fail init with no valid XIM

XOpenIM can fail to find a valid input method, in which case it
returns NULL. Passing a NULL pointer to XCreateIC would cause a
crash, so fail VO init before that happens.

vo/x11_common: remove superfluous msg prefixes

Conflicts:
	video/out/x11_common.c

vo/x11_common: don't require a working input method

Normally, we need this for Xutf8LookupString(). But we can just fall
back to XLookupString(). In fact, the code for this was already there,
the code was just never tested and was actually crashing when active
(see commit 2115c4a).
ao_pulse: set the property media.role=video

Adjusted for the stable branch.

Signed-off-by: wm4 <wm4@nowhere>
ao_pulse: bug fix: goto the correct error handler

Conflicts:
	audio/out/ao_pulse.c
vf: fix filter initialization error check

vf_open returns 0 on error, 1 on success. Oops. Accidentally broken
with 6629a95.
manpage: af_volnorm was renamed
Release 0.1.7