autoload.lua: promote to a builtin script

Of all the scripts located in the TOOLS directory, autoload is miles
away the most popular one. It gets the most contributions by far, and
the feature is clearly fairly popular among users. Instead of forcing
them to manually copy the script into their script folders, make it a
builtin instead. Unlike the other lua scripts, this is disabled by
default given that it's a big behavioral change that is not universally
desirable but users can enable it with a simple line in their configs.

DOCS/man/options.rst

@@ -1027,6 +1027,11 @@ Program Behavior
     Enable the builtin script that lets you select from lists of items (default:
     yes). By default, its keybindings start with the ``g`` key.
 
+``--load-autoload=<yes|no>``
+    Enable the builtin script that scans the directory a file is located in and
+    adds the found files to the playlist before and after the currently playing
+    file (default: no).
+
 ``--player-operation-mode=<cplayer|pseudo-gui>``
     For enabling "pseudo GUI mode", which means that the defaults for some
     options are changed. This option should not normally be used directly, but

options/options.c

@@ -558,6 +558,7 @@ static const m_option_t mp_opts[] = {
         OPT_CHOICE(lua_load_auto_profiles, {"no", 0}, {"yes", 1}, {"auto", -1}),
         .flags = UPDATE_BUILTIN_SCRIPTS},
     {"load-select", OPT_BOOL(lua_load_select), .flags = UPDATE_BUILTIN_SCRIPTS},
+    {"load-autoload", OPT_BOOL(lua_load_autoload), .flags = UPDATE_BUILTIN_SCRIPTS},
 #endif
 
 // ------------------------- stream options --------------------

options/options.h

@@ -176,6 +176,7 @@ typedef struct MPOpts {
     bool lua_load_console;
     int lua_load_auto_profiles;
     bool lua_load_select;
+    bool lua_load_autoload;
 
     bool auto_load_scripts;
 

player/core.h

@@ -437,7 +437,7 @@ typedef struct MPContext {
 
     struct mp_ipc_ctx *ipc_ctx;
 
-    int64_t builtin_script_ids[6];
+    int64_t builtin_script_ids[7];
 
     mp_mutex abort_lock;
 

player/lua.c

@@ -84,6 +84,9 @@ static const char * const builtin_lua_scripts[][2] = {
     },
     {"@select.lua",
 #   include "player/lua/select.lua.inc"
+    },
+    {"@autoload.lua",
+#   include "player/lua/autoload.lua.inc"
     },
     {0}
 };

player/lua/meson.build

@@ -1,6 +1,6 @@
 lua_files = ['defaults.lua', 'assdraw.lua', 'options.lua', 'osc.lua',
              'ytdl_hook.lua', 'stats.lua', 'console.lua', 'auto_profiles.lua',
-             'input.lua', 'fzy.lua', 'select.lua']
+             'input.lua', 'fzy.lua', 'select.lua', 'autoload.lua']
 foreach file: lua_files
     lua_file = custom_target(file,
         input: join_paths(source_root, 'player', 'lua', file),

player/scripting.c

@@ -263,6 +263,7 @@ void mp_load_builtin_scripts(struct MPContext *mpctx)
     load_builtin_script(mpctx, 4, mpctx->opts->lua_load_auto_profiles,
                         "@auto_profiles.lua");
     load_builtin_script(mpctx, 5, mpctx->opts->lua_load_select, "@select.lua");
+    load_builtin_script(mpctx, 6, mpctx->opts->lua_load_autoload, "@autoload.lua");
 }
 
 bool mp_load_scripts(struct MPContext *mpctx)