Don't switch forward and reverse coefficients.
Don't switch forward and reverse coefficients.

1) I think saving the kr as forward and kf as reverse was a mistake.
2) I don't think saving these is necessary anyway, as the underlying 
   arrays are already updated in place.

pierrelb/RMG-Py,nyee/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,chatelak/RMG-Py,nickvandewiele/RMG-Py,chatelak/RMG-Py,nyee/RMG-Py