Checker: pipe & culvert connections

[caspervdw]

The invert levels of pipes and culverts should not differ more than their cross section height.

Unless if there is storage on the node.

[Jonasvsl]

(Nici) : warning if there is a big difference, calculation points need to be added

[Jonasvsl]

As I see it we have two choices:

• Solve this for the user by automatically adding more calculation points and warn the user about the situation
• Give an error with the advice to add more calculation points on these culverts / pipes

I'm in favor of the first option as this is what users will want in most cases, unless there is a typo in the invert level or a dutch situation where people sometimes forget a minus

[caspervdw]

I don't understand the comments by @nvolp and @Jonasvsl ; if the invert levels differ more than the cross section height, the addition of nodes will not make a difference. Please explain!