Add setting for lyric providers and add more providers

Fixes #335

src/lyrics/musixmatchlyricsprovider.h

@@ -0,0 +1,64 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2020, Jonas Kvinge <jonas@jkvinge.net>
+ *
+ * Strawberry is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Strawberry is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef MUSIXMATCHLYRICSPROVIDER_H
+#define MUSIXMATCHLYRICSPROVIDER_H
+
+#include "config.h"
+
+#include <QtGlobal>
+#include <QObject>
+#include <QList>
+#include <QMap>
+#include <QVariant>
+#include <QString>
+#include <QStringList>
+#include <QUrl>
+#include <QJsonArray>
+
+#include "jsonlyricsprovider.h"
+#include "lyricsfetcher.h"
+
+class QNetworkAccessManager;
+class QNetworkReply;
+
+class MusixmatchLyricsProvider : public JsonLyricsProvider {
+  Q_OBJECT
+
+ public:
+  explicit MusixmatchLyricsProvider(QObject *parent = nullptr);
+
+  bool StartSearch(const QString &artist, const QString &album, const QString &title, const quint64 id);
+  void CancelSearch(const quint64 id);
+
+ private:
+  void Error(const QString &error, const QVariant &debug = QVariant());
+
+ private slots:
+  void HandleSearchReply(QNetworkReply *reply, const quint64 id, const QString &artist, const QString &album, const QString &title);
+
+ private:
+  static const char *kSettingsGroup;
+
+ private:
+  QNetworkAccessManager *network_;
+
+};
+
+#endif  // MUSIXMATCHLYRICSPROVIDER_H