Verify data flow in graph

[houshuang]

Completing #259, we need to add more tests

• config of ac/op is valid
  • investigate validation with RJF, obligatory fields, custom validation callbacks etc
• type-check data flow (#170)
• type-check social flow/structure
  • an activity with a certain groupingKey receives socialStructure with that groupingKey, and activityData compatible with that groupingKey (structure: thatGroupingKey, or all) (or no activityData)
  • an activity with structure: all, receives activityData: all (or no activityData)
• no connections where target activity ends before sourceActivity begins
• no overlapping groupingKeys when multiple social operators connected to activity/operator

[houshuang]

Type checking is in the supertest branch, needs more work.