Scenario scenario.json: 3 nodes, 2 links, 1 population.
Nodes:
  0   office           room   200 m²
  1   flight           stair  10.8 m²
  2   street           safe   
Links:
  0   office->flight           door     0.78 persons/s
  1   flight->street           stair    0.91 persons/s
Populations:
  0   office           -> street
Trial run, seed 1: evacuation time 323.0 s; 120 of 120 agents safe.
The scenario is valid.
