can now create upstream to downstream direct connections
unrelevant list elements are grayed-out

grey out Calculate button if basins structure is invalid
use Mermaid Nodes for walls
suffix multiple walls on same basins pair
base Mermaid Nodes on children UIDs
display Mermaid code (debug)
unselect element after deletion
highlight selected element

add basin
remove basin (buggy)
remove wall

Resolve "Documentation des passes à ralentisseurs"

See merge request !87

Refs #398

Refs #398

- Mispelling
- Correct formula for number of baffles

Refs #398

Refs #398

Refs #398