vo_vaapi: fix broken error checks
vo_wayland: drop redundant "const"
ipc: make sure --input-file=/dev/stdin always works

It's not necessarily available on Unix systems other than Linux (sigh).
vo/x11: implement VOCTRL_GET_DISPLAY_NAMES with xrandr names (e.g., "LVDS1")

XRRGetOutputInfo contains a "name" element which corresponds to to the
display names given to the user by the "xrandr" command line
utility. Copy it into the xrandr_display struct for each display.
On VOCTRL_GET_DISPLAY_NAMES, send a copy of the names
of the displays spanned by the mpv window on.
command: add display-names property

Call VOCTRL_GET_DISPLAY_NAMES it when the property is
requested. The vo should return the names of the displays that the mpv
window is covering.  For example, with x11 vos, xrandr names LVDS1,
HDMI1, etc.
vo_opengl: initialize renderer after setting size

This silences the warning:

video/out/gl_video.c:1091:51: runtime error: division by zero

when running with clang -fsanitize=undefined. Division by zero is legal
according to IEEE, but I guess clang doesn't care about standard. While
triggering this warning isn't actually avoided in all cases, it's
avoided in the common case and also makes people shut up about it.
audio: add --audio-client-name option

The main need I see for this is with libmpv - it would be confusing if
some application showed up as "mpv" on whateverthehell PulseAudio uses
it for (generally it does show up on various PA GUI tools).
client API: silence silly clang warning

The values compared here happen to be of unsigned enum types - but the
test is not supposed to break if we somehow force the enum to signed, or
if the compiler happens to use a signed type (as far as I remember, the
exact integer type the compiler can use is implementation-defined).
client: remove redundant assignment

This is set by send_reply().
client API: additional documentation comments

(I guess some of the mpv_event contents turned out relatively awkward.)
command: export the flag whether an option was set on commandline

Can be useful for certain scripts; I think someone requested this.