+ Avoid cyclic dependency of tree items
Merge branch 'master' of ssh://git.code.sf.net/p/free-cad/code
+ clarify documentation of class DockWindowManager
+ switch off mouse propagation of OpenGL widget
+ drag and drop on tree widget
issue 0001469: OpenSCAD import more than one dxf layer

 with the same name

remove all imported dxf geometry
change dxf import object naming to avoid conflicts with group names
Draft: added a continue button to the Point tool - fixes #1386