Added icons to options dialog categories

Some categories do not have icons yet, unfortunately.

src/plugins/cpptools/completionsettingspage.cpp

@@ -70,6 +70,11 @@ QString CompletionSettingsPage::displayCategory() const
     return QCoreApplication::translate("Text Editor", TextEditor::Constants::TEXT_EDITOR_SETTINGS_TR_CATEGORY);
 }
 
+QIcon CompletionSettingsPage::categoryIcon() const
+{
+    return QIcon(QLatin1String(TextEditor::Constants::TEXT_EDITOR_SETTINGS_CATEGORY_ICON));
+}
+
 QWidget *CompletionSettingsPage::createPage(QWidget *parent)
 {
     QWidget *w = new QWidget(parent);