Restore functionality/use of Marker.get_fixed() in MarkerPlacer
Restore functionality/use of Marker.get_fixed() in MarkerPlacer

opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core