add reformat to context menu, formatting width may be changed in preferences

tools/lammps-gui/preferences.h

@@ -83,6 +83,16 @@ private:
     QSettings *settings;
 };
 
+class EditorTab : public QWidget {
+    Q_OBJECT
+
+public:
+    explicit EditorTab(QSettings *settings, QWidget *parent = nullptr);
+
+private:
+    QSettings *settings;
+};
+
 #endif
 
 // Local Variables: