Validation errors are mostly handled in the frontend (by displaying
invalid fields with a red background). There was some code left in the
backend for handling different kinds of errors, and returning custom
error messages from validate(), but the resulting value was not used
anywhere.
- Add a dependency array to section template
- Lift dependency handling from AbstractValue to Node
- Split resolve_depends() into a function handling dependencies of a
node itself (resolve_node_depends()), which now is used for all nodes,
and the existing recursive descent through the node tree
- When any node's dependencies are not satisfied, all descendents are
reset recursively, meaning that an option in a section that is hidden
will always be ignored, as if the option's own dependencies were
unsatisfied
Fixes: #1349
