ArchSectionPlane: Add properties for the line color and the fill color
ArchSectionPlane: Add properties for the line color and the fill color

* Both properties are automatically added to old section planes
  with the help of onDocumentRestored.
* A bit of style clean up to improve the readability of touched code lines.

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master