Optimize BaseTextMark

Instead of each BaseTextMark being a QObject and being connected
to editorOpened, centralize that and distribute the signal
to only the BaseTextMarks that need it.

Change-Id: I3f2783c34a25d78aa335418236850436028bfdf3
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

src/plugins/debugger/breakpointmarker.h

@@ -43,8 +43,6 @@ namespace Internal {
 // The red blob on the left side in the cpp editor.
 class BreakpointMarker : public TextEditor::BaseTextMark
 {
-    Q_OBJECT
-
 public:
     BreakpointMarker(BreakpointModelId id, const QString &fileName, int lineNumber);
     ~BreakpointMarker();