Support more CUE filenames

Fixes #835

src/playlistparsers/cueparser.cpp

@@ -379,3 +379,16 @@ bool CueParser::TryMagic(const QByteArray &data) const {
   return false;
 
 }
+
+QString CueParser::FindCueFilename(const QString &filename) {
+
+  QStringList cue_files = QStringList() << filename + ".cue"
+                                        << filename.section('.', 0, -2) + ".cue";
+
+  for (const QString &cuefile : cue_files) {
+    if (QFileInfo::exists(cuefile)) return cuefile;
+  }
+
+  return QString();
+
+}

src/playlistparsers/cueparser.h

@@ -70,6 +70,8 @@ class CueParser : public ParserBase {
   SongList Load(QIODevice *device, const QString &playlist_path = "", const QDir &dir = QDir(), const bool collection_search = true) const override;
   void Save(const SongList &songs, QIODevice *device, const QDir &dir = QDir(), Playlist::Path path_type = Playlist::Path_Automatic) const override;
 
+  static QString FindCueFilename(const QString &filename);
+
  private:
   // A single TRACK entry in .cue file.
   struct CueEntry {