Drag flow into view-map

This is pretty awful, but will let me wire up items more easily without
needing to do the big refactor into independent menu handlers

internal/flow/flow.go

@@ -92,6 +92,11 @@ func New(assets *assetstore.AssetStore, config *config.Config, ship *ship.Ship)
 	return out, out.exit
 }
 
+func (f *Flow) SetScenario(scenario *scenario.Scenario) {
+	f.current = f.drivers[mainGame]
+	f.scenario = scenario
+}
+
 func (f *Flow) Update(screenX, screenY int) error {
 	if f.exit != nil {
 		return f.exit