player: add loadfile insert-next commands

This commit adds two new commands (`insert-next` and `insert-next-play`)
which mirror the existing commands, `append` and `append-play` in
functionality, with the difference that they insert directly after the
current playlist entry, rather than at the end of the playlist.

This change gives MPV a piece of functionality already found in (for
example) Spotify's media player: "play next". Additionally, using the
new `insert-next` command, users can trivially write a script to play a
new piece of media immediately without otherwise clearing or altering
the remainder of the playlist.

1 files changed, 6 insertions, 0 deletions

diff --git a/DOCS/man/input.rst b/DOCS/man/input.rst
index 6ac9fb2bd5..e79979f243 100644
--- a/DOCS/man/input.rst
+++ b/DOCS/man/input.rst
@@ -469,6 +469,12 @@ Remember to quote string arguments in input.conf (see `Flat command syntax`_).
         Append the file, and if nothing is currently playing, start playback.
         (Always starts with the added file, even if the playlist was not empty
         before running this command.)
+    <insert-next>
+        Insert the file into the playlist, directly after the current entry.
+    <insert-next-play>
+        Insert the file next, and if nothing is currently playing, start playback.
+        (Always starts with the added file, even if the playlist was not empty
+        before running this command.)
 
     The third argument is a list of options and values which should be set
     while the file is playing. It is of the form ``opt1=value1,opt2=value2,..``.