Editor: paint location marker over everything else

The location marker is updated very regularly and especially while
stepping moves one line at a time. Resizing this marker when it enters a
line that already contains a marker is visually distracting. To prevent
this paint the marker over all other markers in that line.

Change-Id: I63ad72384e77eeae4dc6d2e2c2ac77c88da92c56
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/texteditor/textmark.cpp

@@ -409,6 +409,16 @@ void TextMark::setSettingsPage(Id settingsPage)
     m_settingsPage = settingsPage;
 }
 
+bool TextMark::isLocationMarker() const
+{
+    return m_isLocationMarker;
+}
+
+void TextMark::setIsLocationMarker(bool newIsLocationMarker)
+{
+    m_isLocationMarker = newIsLocationMarker;
+}
+
 TextMarkRegistry::TextMarkRegistry(QObject *parent)
     : QObject(parent)
 {