search gui advanced search panel: add checkbox to invert the meaning of the directory filter

src/qtgui/advsearch.ui

@@ -399,6 +399,13 @@
        </property>
       </widget>
      </item>
+     <item row="0" column="1">
+      <widget class="QCheckBox" name="direxclCB">
+       <property name="text">
+        <string>Invert</string>
+       </property>
+      </widget>
+     </item>
     </layout>
    </item>
    <item>

src/qtgui/advsearch_w.cpp

@@ -351,7 +351,8 @@ void AdvSearch::runSearch()
 
     if (!subtreeCMB->currentText().isEmpty()) {
 	QString current = subtreeCMB->currentText();
-	sdata->setTopdir((const char*)subtreeCMB->currentText().toUtf8());
+	sdata->setTopdir((const char*)subtreeCMB->currentText().toUtf8(),
+			 direxclCB->isChecked());
 	// Keep history list clean and sorted. Maybe there would be a
 	// simpler way to do this
 	list<QString> entries;