FEM: Make temp directory default for solver

Previously it would return None if no setting is found (which can
happen if the settings system hasn't been loaded at least once). This
would make some other code fail.

src/Mod/Fem/femsolver/settings.py

@@ -158,12 +158,11 @@ def get_custom_dir():
 
 def get_dir_setting():
     param_group = FreeCAD.ParamGet(_GENERAL_PARAM)
-    if param_group.GetBool("UseTempDirectory"):
-        return TEMPORARY
-    elif param_group.GetBool("UseBesideDirectory"):
+    if param_group.GetBool("UseBesideDirectory"):
         return BESIDE
     elif param_group.GetBool("UseCustomDirectory"):
         return CUSTOM
+    return TEMPORARY
 
 
 ##  @}