scenario: export `ScenarioConfig`

verse/__init__.py

@@ -2,6 +2,6 @@ from verse import agents, sensor, scenario, plotter, map, parser, automaton, ana
 from verse.agents import BaseAgent
 from verse.sensor import BaseSensor
 from verse.map import LaneSegment, LaneMap, Lane
-from verse.scenario import Scenario
+from verse.scenario import Scenario, ScenarioConfig
 
 from verse.plotter import plotter2D, plotter3D