Make DXF export support for LwPolyline more compatible
	modified:   src/Mod/Draft/importDXF.py
Fixed for 2D Hull with Circles ( TestHull1.scad now works )
	modified:   src/Mod/Draft/Draft.py
	modified:   src/Mod/Draft/importDXF.py
	modified:   src/Mod/OpenSCAD/OpenSCADUtils.py
	modified:   src/Mod/OpenSCAD/importCSG.py