FEM: group meshing, add some checks and output to catch some problems
FEM: group meshing, add some checks and output to catch some problems

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