Polish the settings dialog.

Add a title label to the pages. Use QGroupBoxes throughout.
Extend SavedAction to work with checkable QGroupBoxes. Polish UI files,
use common layout for VCS plugins. Performance: Apply only visited
settings pages. Add search keywords.

Task-number: QTCREATOR-26

src/plugins/debugger/gdb/trkoptionspage.cpp

@@ -76,6 +76,8 @@ QWidget *TrkOptionsPage::createPage(QWidget *parent)
     if (!m_widget)
         m_widget = new TrkOptionsWidget(parent);
     m_widget->setTrkOptions(*m_options);
+    if (m_searchKeywords.isEmpty())
+        m_searchKeywords = m_widget->searchKeywords();
     return m_widget;
 }
 
@@ -94,5 +96,10 @@ void TrkOptionsPage::finish()
 {
 }
 
+bool TrkOptionsPage::matches(const QString &s) const
+{
+    return m_searchKeywords.contains(s, Qt::CaseInsensitive);
+}
+
 } // namespace Internal
 } // namespace Designer