add custom sort format

doc/config

@@ -179,6 +179,17 @@
 #tag_editor_album_format = "{(%y) }%b"
 #
 ##
+## Note: Below variables are used for sorting the library browser.
+## The sort mode determines how the song library is sorted, and can
+## be used in combination with a sort format to specify a custom sorting format.
+## Possible values for sort_mode are "name", "mtime" and "format".
+##
+#
+#sort_mode = "name"
+#
+#sort_format = "{%b~%n}|{~%n}|{~~%t}|{~~%f}"
+#
+##
 ## Note: Below variables are for alternative version of user's interface.
 ## Their syntax supports all tags and colors listed above plus some extra
 ## markers used for text attributes. They are followed by character '$'.

doc/ncmpcpp.1

@@ -131,6 +131,12 @@ Format for albums' list in Tag editor.
 .TP 
 .B song_window_title_format
 Song format for window title.
+.TP
+.B sort_mode
+Determines the sort mode for the song library. Possible values are "name", "mtime" and "format".
+.TP
+.B sort_format
+Format to use for sorting the song library. For this option to be effective, sort_mode must be set to "format".
 .TP 
 .B external_editor = PATH
 Path to external editor used to edit lyrics.
@@ -295,7 +301,7 @@ If enabled, bitrate of currently playing song will be displayed in statusbar.
 If enabled, remaining time of currently playing song will be be displayed in statusbar instead of elapsed time.
 .TP 
 .B ignore_leading_the = yes/no
-If enabled, word "the" at the beginning of tags/filenames will be ignored while sorting items.
+If enabled, word "the" at the beginning of tags/filenames will be ignored while sorting items. Note that this doesn't currently work with custom sorting formats.
 .TP 
 .B use_console_editor = yes/no
 If your external editor is console application, you need to enable it.