player: write file name to the watch later config file

This simply writes the file name as a comment to the top of the watch later
config file.

It can be useful to the user for determining whether a watch later config file
can be manually removed (e.g. in case the corresponding media file has been
deleted) or not.
osd/libass: use BorderStyle=4 for background

Avoids (some) overlaps. Hopefully fixes #822.
wayland: remove stub for unimplemented function
osc: keep track of the "fullscreen" state when it changes

This avoids having to poll the "fullscreen" property in the tick
callback.
command: format_bitrate: fix conversion to kbits and mbits

Bitrates are now expressed in bits/second. This commit fixes conversions
which assumed it was still in bytes/second.

Signed-off-by: wm4 <wm4@nowhere>
audio/out/push: don't attempt to fill AO buffer when paused

Doing so will implicitly resume playback. Broken in commit 5929dc45.
filter_kernels: add nearest neighbour scaling

This is useful for playing content containing pixel art that hasn't been
pre-scaled, such as TASVideos' high quality encodes. The implementation is
lifted from <https://code.google.com/p/glumpy/source/browse/glumpy/image/filter.py#413>.
filter_kernels: fix nearest scaler

The previous commit assumed the filter would be 1x1 (then constant
weight is correct) - but our code in fact uses at least a 2x2 filter. A
1x1 filter would generally be useless, except for nearest scaling - so
it didn't exist.

Insteasd of adding such a 1x1 filter, just turn the nearest weight
function into a scare function, which should take care of the issue.
lua: make warning about unknown scripts -v only
Merge branch 'master' of https://github.com/mpv-player/mpv