Added icons to options dialog categories

Some categories do not have icons yet, unfortunately.

src/plugins/mercurial/optionspage.cpp

@@ -107,6 +107,11 @@ QString OptionsPage::displayCategory() const
     return QCoreApplication::translate("VCSBase", VCSBase::Constants::VCS_SETTINGS_TR_CATEGORY);
 }
 
+QIcon OptionsPage::categoryIcon() const
+{
+    return QIcon(); // TODO: Icon for Version Control
+}
+
 QWidget *OptionsPage::createPage(QWidget *parent)
 {
     if (!optionsPageWidget)