Exchange line table and checks

[caspervdw]

@Jonasvsl @martijn-siemerink

Two issues:

the name

• shadow_line
• exchange_line
• domain_exchange_line

What do you think? I think I like exchange_line.

backwards compatibility:

Connected points can currently also apply to pipes, culverts and connection nodes (manholes and 1D boundary conditions). Shadow lines intend to replace the connected points. But if we only do shadow lines for channels, we would ignore any adapted 1D-2D connections for pipes/culverts/nodes. See also https://github.com/nens/threedigrid-builder/issues/275

We could extend the design to also be able to have shadow lines for pipes, culverts and connection nodes.

[Jonasvsl]

exchange_line has a better ring to it than shadow line.

not sure whether we need to extend the design to have shadow lines for pipes, culverts and connection nodes. @leendertvanwolfswinkel what do you think? I remember I had a nice theory about it being handy for connection nodes in urban areas but my assumptions where proven to be incorrect. So for me it is hard to see the benefit.

[caspervdw]

One question:

• I'd like to prevent the user from inserting the wrong channel id (otherwise you may connect entirely different model regions). Is a warning when the distance between exchange line and channel is too large a good idea? What threshold do we take? @leendertvanwolfswinkel @Jonasvsl

[leendertvanwolfswinkel]

Sounds good, I would propose to use a pretty lange distance. We don't want a high number of false warnings.

I think 500 m would be a good value? I.e. always wrong.