Remove some unneeded includes, etc

src/lyrics/musixmatchlyricsprovider.h

@@ -24,13 +24,8 @@
 
 #include <QtGlobal>
 #include <QObject>
-#include <QList>
-#include <QMap>
 #include <QVariant>
 #include <QString>
-#include <QStringList>
-#include <QUrl>
-#include <QJsonArray>
 
 #include "jsonlyricsprovider.h"
 #include "lyricsfetcher.h"
@@ -53,9 +48,6 @@ class MusixmatchLyricsProvider : public JsonLyricsProvider {
  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_;