Routing table validation helpers.
Fix Go API tests.
Validate in RoutingTableHelper.add_entry().
Remove unnecessary TODO.
Merge branch 'feature/issue-559-better-routing-table-validation' into develop
Merge branch 'develop' into develop-frontend
Put keyword router endpoints on the correct side.
Merge branch 'feature/issue-558-fix-router-directionality' into develop-frontend
Merge branch 'develop-frontend' into feature/issue-555-add-routers-to-routing-screen
Revert "Put keyword router endpoints on the correct side."

This reverts commit b031ff9e657a84408327f8cfe178d22ce988639a.