Restore some Q_OBJECT macros (#516)

Reverts commit 08dfcc, and restores part of the changes.

This resolves #516 (closed).

GUI/View/SampleDesigner/MaterialInplaceForm.h

@@ -23,7 +23,6 @@ class SampleEditorController;
 
 //! Form to select a material and to edit it in-place
 class MaterialInplaceForm : public QWidget {
-    Q_OBJECT
 public:
     MaterialInplaceForm(QWidget* parent, ItemWithMaterial* item, SampleEditorController* ec);