Add context menu to hide columns in file manager

src/filemanager.h

@@ -25,9 +25,12 @@ private:
 
 class DirFileSystemModel : public QFileSystemModel
 {
+    Q_OBJECT
     mutable QCache<QString, ImageInfoData> *_cache = nullptr;
     static QCache<QString, ImageInfoData>* getCacheInstance();
     QModelIndex _dir;
+    QStringList _fitsKeywords;
+    bool _loadFitsKeywords = true;
 public:
     explicit DirFileSystemModel(QObject *parent = nullptr);
     void setDir(const QString &path);
@@ -37,6 +40,8 @@ public:
     QVariant data(const QModelIndex &index, int role) const override;
     QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
     bool hasChildren(const QModelIndex &parent) const override;
+public slots:
+    void loadFitsKeywords(bool enable);
 };
 
 class DirView : public QTreeView
@@ -49,6 +54,8 @@ public:
     void setDir(const QString &path);
     QString dir() const;
     void setOpenFilter(const QSet<QString> &openFilter);
+public slots:
+    void headerContextMenu(const QPoint &pos);
 signals:
     void dirChanged(const QString &path);
     void openFile(const QString &path);