STYLE: Simplify qMRMLScene canBeAChild/canBeAParent implementation

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23380 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: Expose qMRMLSceneModel mrml/setMRMLScene methods to python.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23381 3bd1e089-480b-0410-8dfb-8563597acbee
STYLE: Elaborate doxygen documentation of qMMRLSCeneModel::nodeIndex

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23382 3bd1e089-480b-0410-8dfb-8563597acbee