Polish the QtWidgets/Player example.

Point the file dialog to the Movies folder.
Add command proper command line handling.
Change the logic to use QUrl everywhere.

Change-Id: I1e54e600187153f52a55e3a381a24e4f2eeda3ab
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>

examples/multimediawidgets/player/player.h

@@ -69,6 +69,10 @@ public:
     Player(QWidget *parent = 0);
     ~Player();
 
+    bool isPlayerAvailable() const;
+
+    void addToPlaylist(const QList<QUrl> urls);
+
 signals:
     void fullScreenChanged(bool fullScreen);
 
@@ -93,7 +97,6 @@ private slots:
 #ifndef PLAYER_NO_COLOROPTIONS
     void showColorDialog();
 #endif
-    void addToPlaylist(const QStringList &fileNames);
 
 private:
     void setTrackInfo(const QString &info);