FEM: Make sure ccx working dir is set

Also TestFem and check_prerequisities are corrected

Signed-off-by: Przemo Firszt <przemo@firszt.eu>

src/Mod/Fem/InitGui.py

@@ -58,6 +58,23 @@ class FemWorkbench (Workbench):
                     FreeCAD.Console.PrintError("CalculiX ccx binary not found! Please set it manually in FEM preferences.\n")
             except Exception as e:
                 FreeCAD.Console.PrintError(e.message)
+        fem_prefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem")
+
+        import os
+        working_dir = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem").GetString("WorkingDir")
+        if not (os.path.isdir(working_dir)):
+            try:
+                os.makedirs(working_dir)
+            except:
+                print ("Dir \'{}\' from FEM preferences doesn't exist and cannot be created.".format(working_dir))
+                import tempfile
+                working_dir = tempfile.gettempdir()
+                print ("Dir \'{}\' will be used instead.".format(working_dir))
+        if working_dir:
+            FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem").SetString("WorkingDir", working_dir)
+        else:
+            FreeCAD.Console.PrintError("Setting working directory \'{}\' for ccx failed!\n")
+
 
     def GetClassName(self):
         return "FemGui::Workbench"