Assumptions on interface names

[MakisH]

To the extent I understand:

• CalculiX requires node groups to be named starting with N: NwetSurface
• The adapter takes the names without the N (wetSurface) and automatically "converts it to CalculiX format" (i.e., prepends the N).

We should:

1. Check if the first assumption really still holds
2. Not ask the user to remove the N, if that is part of the name