PartDesign (core): fix inability to deactivate active object
PartDesign (core): fix inability to deactivate active object

It was impossible to deactivate active object (Part or Body) with:
Gui.ActiveDocument.ActiveView.setActiveObject("pdbody",None)

maurerpe/FreeCAD,timthelion/FreeCAD,Fat-Zer/FreeCAD_sf_master,bblacey/FreeCAD-MacOS-CI,wood-galaxy/FreeCAD,bblacey/FreeCAD-MacOS-CI,usakhelo/FreeCAD,wood-galaxy/FreeCAD,wood-galaxy/FreeCAD,chrisjaquet/FreeCAD,bblacey/FreeCAD-MacOS-CI,maurerpe/FreeCAD,chrisjaquet/FreeCAD,wood-galaxy/FreeCAD,maurerpe/FreeCAD,bblacey/FreeCAD-MacOS-CI,Fat-Zer/FreeCAD_sf_master,maurerpe/FreeCAD,bblacey/FreeCAD-MacOS-CI,timthelion/FreeCAD,bblacey/FreeCAD-MacOS-CI,timthelion/FreeCAD,bblacey/FreeCAD-MacOS-CI,Fat-Zer/FreeCAD_sf_master,maurerpe/FreeCAD,Fat-Zer/FreeCAD_sf_master,chrisjaquet/FreeCAD,timthelion/FreeCAD,timthelion/FreeCAD,Fat-Zer/FreeCAD_sf_master,wood-galaxy/FreeCAD,usakhelo/FreeCAD,chrisjaquet/FreeCAD,chrisjaquet/FreeCAD,chrisjaquet/FreeCAD,usakhelo/FreeCAD,usakhelo/FreeCAD,timthelion/FreeCAD,usakhelo/FreeCAD,usakhelo/FreeCAD,chrisjaquet/FreeCAD,wood-galaxy/FreeCAD,usakhelo/FreeCAD