Add save all playlists action

src/playlist/playlistmanager.cpp

@@ -650,3 +650,15 @@ void PlaylistManager::RateCurrentSong(const float rating) {
 void PlaylistManager::RateCurrentSong2(const int rating) {
   RateCurrentSong(static_cast<float>(rating) / 5.0F);
 }
+
+void PlaylistManager::SaveAllPlaylists() {
+
+  const QString path = QFileDialog::getExistingDirectory(nullptr, tr("Select directory for the playlists"), QDir::homePath(), QFileDialog::ShowDirsOnly | QFileDialog::DontResolveSymlinks);
+
+  for (QMap<int, Data>::const_iterator it = playlists_.constBegin(); it != playlists_.constEnd(); ++it) {
+    const Data &data = *it;
+    const QString filepath = path + "/" + data.name + ".m3u";
+    Save(it.key(), filepath, Playlist::Path_Absolute);
+  }
+
+}