Material: fixes several issues

* fix warning -Wunused-variable
* fix warning -Wreorder-ctor
* fix warning -Wunused-but-set-variable
* fix uic warning for DlgDisplayProperties.ui
* rename the target MateriaTestLib ALL (note the typo and the already existing MaterialTestLib ALL) to MaterialTest ALL
  drop the hard dependency to the Part module: The document is checked for a property ShapeMaterial of type Materials::PropertyMaterial.
  An alternative could be to cast to GeoFeature and use the methods getMaterialAppearance() and setMaterialAppearance()

src/Mod/Material/Gui/MaterialTreeWidget.cpp

@@ -195,7 +195,6 @@ bool MaterialTreeWidget::findInTree(const QStandardItem& node,
     }
 
     if (node.hasChildren()) {
-        int rows = node.rowCount();
         for (int i = 0; i < node.rowCount(); i++) {
             auto child = node.child(i);
             if (findInTree(*child, index, uuid)) {
@@ -458,4 +457,4 @@ void MaterialTreeWidget::onDoubleClick(const QModelIndex& index)
         auto uuid = item->data(Qt::UserRole).toString();
         updateMaterial(uuid);
     }
-}
+}