update visualization code in footsteps driver that handles terrain slices
update visualization code in footsteps driver that handles terrain slices

RussTedrake/director,gizatt/director,RobotLocomotion/director,mithrandir123/director,gizatt/director,mithrandir123/director,rdeits/director,edowson/director,patmarion/director,mitdrc/director,RobotLocomotion/director,openhumanoids/director,RussTedrake/director,mitdrc/director,RussTedrake/director,manuelli/director,mithrandir123/director,manuelli/director,RussTedrake/director,openhumanoids/director,patmarion/director,rdeits/director,RobotLocomotion/director,gizatt/director,RussTedrake/director,RobotLocomotion/director,openhumanoids/director,rdeits/director,edowson/director,edowson/director,mithrandir123/director,empireryan/director,patmarion/director,patmarion/director,openhumanoids/director,manuelli/director,manuelli/director,empireryan/director,empireryan/director,RobotLocomotion/director,edowson/director,mitdrc/director,empireryan/director,gizatt/director,rdeits/director,edowson/director,manuelli/director,gizatt/director,rdeits/director,openhumanoids/director,empireryan/director,mithrandir123/director,mitdrc/director,mitdrc/director,patmarion/director