added check for holes to mesh validation dialog in GUI

Applications/DataExplorer/DataView/MeshAnalysis.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>483</width>
-    <height>650</height>
+    <height>787</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -348,6 +348,13 @@
         </property>
        </widget>
       </item>
+      <item row="5" column="0" colspan="4">
+       <widget class="QLabel" name="meshHoleOutputLabel">
+        <property name="text">
+         <string/>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>

Applications/DataExplorer/DataView/MeshAnalysisDialog.cpp

@@ -60,6 +60,10 @@ void MeshAnalysisDialog::on_startButton_pressed()
 		*mesh, this->zeroVolumeThreshold->text().toDouble() + std::numeric_limits<double>::epsilon()));
 	this->elementsGroupBox->setTitle("Elements (out of " + QString::number(mesh->getNElements()) + ")");
 	this->elementsMsgOutput(element_error_codes);
+	
+	unsigned const n_holes (MeshLib::MeshValidation::detectHoles(*mesh));
+	if (n_holes>0)
+		this->meshHoleOutputLabel->setText("<strong>" + QString::number(n_holes) + " hole(s) found within the mesh</strong>");
 }
 
 void MeshAnalysisDialog::nodesMsgOutput(std::vector<std::size_t> const& node_ids, std::vector<std::size_t> const& collapsibleNodeIds)