tag/Type: add TAG_GROUPING

Map ID3 "TIT1" to this new core tag type.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/563

NEWS

@@ -2,6 +2,8 @@ ver 0.22 (not yet released)
 * protocol
   - "findadd"/"searchadd"/"searchaddpl" support the "sort" and
     "window" parameters
+* tags
+  - new tag "Grouping" (for ID3 "TIT1")
 * input
   - ffmpeg: allow partial reads
 * filter

doc/protocol.rst

@@ -274,6 +274,9 @@ The following tags are supported by :program:`MPD`:
 * **date**: the song's release date. This is usually a 4-digit year.
 * **composer**: the artist who composed the song.
 * **performer**: the artist who performed the song.
+* **grouping**: "used if the sound belongs to a larger category of
+  sounds/music" (`from the IDv2.4.0 TIT1 description
+  <http://id3.org/id3v2.4.0-frames>`_).
 * **comment**: a human-readable comment about this song. The exact meaning of this tag is not well-defined.
 * **disc**: the decimal disc number in a multi-disc album.
 * **label**: the name of the label or publisher.

src/tag/Id3Scan.cxx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -317,6 +317,7 @@ scan_id3_tag(const struct id3_tag *tag, TagHandler &handler) noexcept
 	tag_id3_import_text(tag, "TPE3", TAG_PERFORMER,
 			    handler);
 	tag_id3_import_text(tag, "TPE4", TAG_PERFORMER, handler);
+	tag_id3_import_text(tag, "TIT1", TAG_GROUPING, handler);
 	tag_id3_import_comment(tag, ID3_FRAME_COMMENT, TAG_COMMENT,
 			       handler);
 	tag_id3_import_text(tag, ID3_FRAME_DISC, TAG_DISC,

src/tag/Id3Scan.hxx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify

src/tag/Names.c

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -34,6 +34,7 @@ const char *const tag_item_names[TAG_NUM_OF_ITEM_TYPES] = {
 	[TAG_ORIGINAL_DATE] = "OriginalDate",
 	[TAG_COMPOSER] = "Composer",
 	[TAG_PERFORMER] = "Performer",
+	[TAG_GROUPING] = "Grouping",
 	[TAG_COMMENT] = "Comment",
 	[TAG_DISC] = "Disc",
 	[TAG_LABEL] = "Label",

src/tag/Type.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -49,6 +49,7 @@ enum TagType
 	TAG_ORIGINAL_DATE,
 	TAG_COMPOSER,
 	TAG_PERFORMER,
+	TAG_GROUPING,
 	TAG_COMMENT,
 	TAG_DISC,
 	TAG_LABEL,