Make correct use of "gpu" option in SegmentModel.simulate_oxdna(); thanks to...

Make correct use of "gpu" option in SegmentModel.simulate_oxdna(); thanks to Elija Feigl catching the issue

mrdna/segmentmodel.py

@@ -4156,6 +4156,7 @@ time_scale = linear
                                     trajectory_file = "{}/{}.dat".format(output_directory,output_name),
                                     last_conf_file = last_conf_file,
                                     log_file="{}/{}.log".format(output_directory,output_name),
+                                    gpu = gpu,
                                     **oxdna_args)
             # os.sync()
             ## TODO: call oxdna