Synopsis
		sftraveltimelen < dist.rsf time=time.rsf dept=dept.rsf len=lent.rsf > imagt.rsf xsrc= tolz= tolx= interpolate= timez0=

Parameters
		file dept= auxiliary input file name   int interpolate=   file len= auxiliary input file name   file time= auxiliary input file name   string timez0=   float tolx=   float tolz=   float xsrc=