Implement new graph API
New API doc merged in c18ac728, this is its implementation.
- Create dedicated 'Edges' class for edge restriction
- Add '*' syntax
- Update visit/ unit tests
- Add visit/ sub-endpoints (nodes/ and paths/)
- Add walk/ endpoint
Unit tests are still missing for 'visit/nodes/' and 'walk/', but I might rework/refactor unit testing code.
Migrated from D1668 (view on Phabricator)