BUG: Fixed markups module GUI on batch update

When markups are added between start/end modify calls then vtkMRMLMarkupsNode::MarkupAddedEvent is called only once,
with NULL calldata. In this case we need to do a full update of the GUI, not just add a new line.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25396 3bd1e089-480b-0410-8dfb-8563597acbee