inpout.conf: make shift+o toggle between 2 states only

The "osd" command cycles between 4 states (OSD level 0-3), which is
probably confusing and inconvenient. OSD levels 0 and 2 are rarely
needed. I would claim there is normally not much of a need to completely
disable OSD by setting level 0 during playback. Level 2 is just slightly
less information than level 3, and I'm not sure why it exists at all.

Change it so that it toggles between level 3 and 1. Note that this
ignores the default OSD level. If the default is 3, the first use of
this key will set it to 3 again. Just assume 1 is the default. If
someone complains, this could be improved.

DOCS/man/mpv.rst

@@ -116,7 +116,7 @@ o (also P)
     Show progression bar, elapsed time and total duration on the OSD.
 
 O
-    Toggle OSD states: none / seek / seek + timer / seek + timer + total time.
+    Toggle OSD states between normal and playback time/duration.
 
 d
     Toggle frame dropping states: none / skip display / skip decoding (see

etc/input.conf

@@ -79,7 +79,7 @@
 #> playlist-next                        # skip to next file
 #ENTER playlist-next                    # skip to next file
 #< playlist-prev                        # skip to previous file
-#O osd                                  # cycle through OSD mode
+#O no-osd cycle_values osd-level 3 1    # cycle through OSD mode
 #o show-progress
 #P show-progress
 #I show-text "${filename}"              # display filename in osd

etc/restore-old-bindings.conf

@@ -9,6 +9,10 @@
 #
 # Older installations use ~/.mpv/input.conf instead.
 
+# changed in mpv 0.10.0
+
+O osd
+
 # changed in mpv 0.7.0
 
 ENTER playlist_next force