Fix timeline seeking not reflected on effect stack.

Related to #159

src/monitor/glwidget.h

@@ -182,7 +182,6 @@ signals:
     void lockMonitor(bool);
     void passKeyEvent(QKeyEvent *);
     void panView(const QPoint &diff);
-    void consumerPosition(int);
     void activateMonitor();
 
 protected:

src/monitor/monitor.cpp

@@ -159,7 +159,6 @@ Monitor::Monitor(Kdenlive::MonitorId id, MonitorManager *manager, QWidget *paren
     connect(m_glMonitor, &GLWidget::passKeyEvent, this, &Monitor::doKeyPressEvent);
     connect(m_glMonitor, &GLWidget::panView, this, &Monitor::panView);
     connect(m_glMonitor->getControllerProxy(), &MonitorProxy::requestSeek, this, &Monitor::processSeek, Qt::DirectConnection);
-    connect(m_glMonitor, &GLWidget::consumerPosition, this, &Monitor::seekPosition, Qt::DirectConnection);
     connect(m_glMonitor->getControllerProxy(), &MonitorProxy::positionChanged, this, &Monitor::slotSeekPosition);
     connect(m_glMonitor, &GLWidget::activateMonitor, this, &AbstractMonitor::slotActivateMonitor, Qt::DirectConnection);
     m_videoWidget = QWidget::createWindowContainer(qobject_cast<QWindow *>(m_glMonitor));
@@ -2067,6 +2066,7 @@ void Monitor::reconfigure()
 
 void Monitor::slotSeekPosition(int pos)
 {
+    emit seekPosition(pos);
     m_timePos->setValue(pos);
     checkOverlay();
 }