ffmpeg.c: rename map_meta_data option to map_metadata

It's consistent with the -metadata option and easier to write.
Signed-off-by: Janne Grunau <janne-ffmpeg@jannau.net>

doc/ffmpeg.texi

@@ -628,7 +628,10 @@ Just enumerate the input streams in the order you want them in the output.
 @var{sync_stream_id} if specified sets the input stream to sync
 against.
 @item -map_meta_data @var{outfile}[,@var{metadata}]:@var{infile}[,@var{metadata}]
-Set meta data information of @var{outfile} from @var{infile}. Note that those
+Deprecated, use @var{-map_metadata} instead.
+
+@item -map_metadata @var{outfile}[,@var{metadata}]:@var{infile}[,@var{metadata}]
+Set metadata information of @var{outfile} from @var{infile}. Note that those
 are file indices (zero-based), not filenames.
 Optional @var{metadata} parameters specify, which metadata to copy - (g)lobal
 (i.e. metadata that applies to the whole file), per-(s)tream, per-(c)hapter or
@@ -644,7 +647,7 @@ file index can be used to create a dummy mapping that just disables automatic co
 For example to copy metadata from the first stream of the input file to global metadata
 of the output file:
 @example
-ffmpeg -i in.ogg -map_meta_data 0:0,s0 out.mp3
+ffmpeg -i in.ogg -map_metadata 0:0,s0 out.mp3
 @end example
 @item -map_chapters @var{outfile}:@var{infile}
 Copy chapters from @var{infile} to @var{outfile}. If no chapter mapping is specified,

ffmpeg.c

@@ -3013,7 +3013,7 @@ static void parse_meta_type(char *arg, char *type, int *index, char **endptr)
         *type = 'g';
 }
 
-static void opt_map_meta_data(const char *arg)
+static void opt_map_metadata(const char *arg)
 {
     AVMetaDataMap *m, *m1;
     char *p;
@@ -3039,6 +3039,13 @@ static void opt_map_meta_data(const char *arg)
         metadata_chapters_autocopy = 0;
 }
 
+static void opt_map_meta_data(const char *arg)
+{
+    fprintf(stderr, "-map_meta_data is deprecated and will be removed soon. "
+                    "Use -map_metadata instead.\n");
+    opt_map_metadata(arg);
+}
+
 static void opt_map_chapters(const char *arg)
 {
     AVChapterMap *c;
@@ -4197,7 +4204,10 @@ static const OptionDef options[] = {
     { "i", HAS_ARG, {(void*)opt_input_file}, "input file name", "filename" },
     { "y", OPT_BOOL, {(void*)&file_overwrite}, "overwrite output files" },
     { "map", HAS_ARG | OPT_EXPERT, {(void*)opt_map}, "set input stream mapping", "file:stream[:syncfile:syncstream]" },
-    { "map_meta_data", HAS_ARG | OPT_EXPERT, {(void*)opt_map_meta_data}, "set meta data information of outfile from infile", "outfile[,metadata]:infile[,metadata]" },
+    { "map_meta_data", HAS_ARG | OPT_EXPERT, {(void*)opt_map_meta_data}, "DEPRECATED set meta data information of outfile from infile",
+      "outfile[,metadata]:infile[,metadata]" },
+    { "map_metadata", HAS_ARG | OPT_EXPERT, {(void*)opt_map_metadata}, "set metadata information of outfile from infile",
+      "outfile[,metadata]:infile[,metadata]" },
     { "map_chapters",  HAS_ARG | OPT_EXPERT, {(void*)opt_map_chapters},  "set chapters mapping", "outfile:infile" },
     { "t", OPT_FUNC2 | HAS_ARG, {(void*)opt_recording_time}, "record or transcode \"duration\" seconds of audio/video", "duration" },
     { "fs", HAS_ARG | OPT_INT64, {(void*)&limit_filesize}, "set the limit file size in bytes", "limit_size" }, //