Synopsis
		sftraveltime2d < dist.rsf time=time.rsf dept=dept.rsf len=lent.rsf > imagt.rsf xsrc= tolz= tolx= frontt0= frontdt= frontnt= fronteps= interpolate= timez0= minpath= front= eik=

Parameters
		file dept= auxiliary input file name   string eik=   string front=   float frontdt=   float fronteps=   int frontnt=   float frontt0=   int interpolate= first arrivals   file len= auxiliary input file name   string minpath=   file time= auxiliary input file name   string timez0=   float tolx=   float tolz=   float xsrc=