[Feature] Playlis to cue plugin

generate valid cue files from a playlist

uses remarks to store extra id3 info and display and playlist index

Change-Id: I00c9f6389445bb601dde6eb8f36157044024f8cb

apps/plugin.c

@@ -841,6 +841,7 @@ static const struct plugin_api rockbox_api = {
     filetype_get_plugin,
     playlist_entries_iterate,
     lang_is_rtl,
+    get_codec_string,
 };
 
 static int plugin_buffer_handle;