Attacher: make Placement read-only when attached
Attacher: make Placement read-only when attached

Read-onlyness of Placement and superPlacement properties is now
dynamically controlled by MapMode property value.

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