FEM: some Python constraint VP, add import of FemGui to get the icon in TreeView when there is no analysis and Fem is not loaded

src/Mod/Fem/femguiobjects/_ViewProviderFemElementGeometry2D.py

@@ -29,7 +29,8 @@ __url__ = "http://www.freecadweb.org"
 
 import FreeCAD
 import FreeCADGui
-
+import FemGui  # needed to display the icons in TreeView
+False if False else FemGui.__name__  # dummy usage of FemGui for flake8, just returns 'FemGui'
 
 # for the panel
 from PySide import QtCore