Aligned to new Part.Line behaviour FC_0.17
Aligned to new Part.Line behaviour FC_0.17

aligned assembly2 to the new Part.Line behaviour for FC_0.17 (compatible with FC_0.16)
FC reference commit
https://github.com/FreeCAD/FreeCAD/commit/81c3bc6ef56e97954319f7d8a9343aa579f3013b
FC forum references
https://forum.freecadweb.org/viewtopic.php?f=28&t=19441&p=159881#p159865
https://forum.freecadweb.org/viewtopic.php?f=3&t=13619&start=50#p159832
hamish2014/FreeCAD_assembly2