options: rename --play-dir to --play-direction

--play-dir sounds like it has something to do with directories so change
it. The play_dir variable is used a bunch everywhere internally so
whatever just leave it alone instead of renaming that.

DOCS/interface-changes.rst

@@ -106,6 +106,7 @@ Interface changes
     - rename `--sub-ass-force-style` to `--sub-ass-style-overrides`
     - rename `--screenshot-directory` to `--screenshot-dir`
     - rename `--watch-later-directory` to `--watch-later-dir`
+    - rename `--play-dir` to `--play-direction`
  --- mpv 0.36.0 ---
     - add `--target-contrast`
     - Target luminance value is now also applied when ICC profile is used.

DOCS/man/options.rst

@@ -484,7 +484,7 @@ Playback Control
     of them fails. This doesn't affect playback of audio-only or video-only
     files.
 
-``--play-dir=<forward|+|backward|->``
+``--play-direction=<forward|+|backward|->``
     Control the playback direction (default: forward). Setting ``backward``
     will attempt to play the file in reverse direction, with decreasing
     playback time. If this is set on playback starts, playback will start from
@@ -701,7 +701,7 @@ Playback Control
 ``--demuxer-backward-playback-step=<seconds>``
     Number of seconds the demuxer should seek back to get new packets during
     backward playback (default: 60). This is useful for tuning backward
-    playback, see ``--play-dir`` for details.
+    playback, see ``--play-direction`` for details.
 
     Setting this to a very low value or 0 may make the player think seeking is
     broken, or may make it perform multiple seeks.

options/options.c

@@ -522,7 +522,7 @@ static const m_option_t mp_opts[] = {
     {"end", OPT_REL_TIME(play_end)},
     {"length", OPT_REL_TIME(play_length)},
 
-    {"play-dir", OPT_CHOICE(play_dir,
+    {"play-direction", OPT_CHOICE(play_dir,
         {"forward", 1}, {"+", 1}, {"backward", -1}, {"-", -1})},
 
     {"rebase-start-time", OPT_BOOL(rebase_start_time)},
@@ -886,6 +886,7 @@ static const m_option_t mp_opts[] = {
 
     {"", OPT_SUBSTRUCT(encode_opts, encode_config)},
 
+    {"play-dir", OPT_REPLACED("play-direction")},
     {"screenshot-directory", OPT_REPLACED("screenshot-dir")},
     {"sub-forced-only", OPT_REPLACED("sub-forced-events-only")},
     {"watch-later-directory", OPT_REPLACED("watch-later-dir")},