COMP: Fix warnings: class declared with greater visibility than the type of its field
COMP: Fix warnings: class declared with greater visibility than the type of its field


This commit fixes warnings like the following:

```
In file included from /tmp/DTIPrep/src/GMainWindow.h:6:0,
                 from /tmp/DTIPrep/src/main.cxx:11:
/tmp/DTIPrep/src/IntensityMotionCheckPanel.h:21:7: warning: ‘IntensityMotionCheckPanel’ declared with greater visibility than the type of its field ‘IntensityMotionCheckPanel::QCedDwiReader’ [-Wattributes]
 class IntensityMotionCheckPanel : public QDockWidget,
       ^
In file included from /tmp/DTIPrep/src/main.cxx:11:0:
/tmp/DTIPrep/src/GMainWindow.h:57:7: warning: ‘GMainWindow’ declared with greater visibility than the type of its field ‘GMainWindow::DwiReader’ [-Wattributes]
 class GMainWindow : public QMainWindow, private Ui_MainWindow
       ^
/tmp/DTIPrep/src/GMainWindow.h:57:7: warning: ‘GMainWindow’ declared with greater visibility than the type of its field ‘GMainWindow::QCedDwiReader’ [-Wattributes]
In file included from /tmp/DTIPrep/src/GMainWindow.h:6:0,
                 from /tmp/DTIPrep/src/GMainWindow.cxx:3:
/tmp/DTIPrep/src/IntensityMotionCheckPanel.h:21:7: warning: ‘IntensityMotionCheckPanel’ declared with greater visibility than the type of its field ‘IntensityMotionCheckPanel::QCedDwiReader’ [-Wattributes]
 class IntensityMotionCheckPanel : public QDockWidget,
       ^
```

NIRALUser/DTIPrep,NIRALUser/DTIPrep