planExporter.TreeWalkPlanExporter: split exportPlan() method into smaller pieces for more flexibility in derived classes
planExporter.TreeWalkPlanExporter: split exportPlan() method into smaller pieces for more flexibility in derived classes

xgds/xgds_planner2,xgds/xgds_planner2,xgds/xgds_planner2,xgds/xgds_planner2