Synopsis
		sfzmarch < vel.rsf > out.rsf na= da= a0= order=3 scheme=2 verb=n what=

Parameters
		float a0= starting velocity   float da= angle sampling   int na= angle samples   int order=3 interpolation order   int scheme=2 finite-difference order   bool verb=n [y/n] verbosity   string what= what to compute (t,x,z,a)