Add -non-dc flag to mtutil for scalar seismic moment
Add -non-dc flag to mtutil for scalar seismic moment

By default, the scalar seismic moment will be calculated using the
two largest magnitude eigenvalues (as done in the Global Centroid
Moment Tensor catalog). Now, the -non-dc flag specifies using all
three eigenvalues to calculate the seismic moment (as done by the
USGS and for GMT psmeca scaling).

mherman09/Hdef,mherman09/Hdef,mherman09/Hdef