Handle "too short" exchange lines

[caspervdw]

If an exchange line is too short, a large part of a channel will exchange with the end of the exchange line. Somethign like this:

How do we handle this?

Two options;

• forbid too short exchange lines in the modelchecker
• ignore an exchange line if the 1D-2D line would exchange with the end of the exchange line

[caspervdw]

Discussed with the customer; we are not going to be smart here and maintain the current situation.

We do add a warning when the exchange line length < 80% of the channel length.