Add second 1d turbulent_scales routine for GFDL

The old compute_turbulent_scales_1d routine is now
compute_turbulent_scales_1d_sigma (because it takes a vector sigma input) and
the routine introduced by Zhi Liang to take a scalar sigma but vector OBL_depth
is compute_turbulent_scales_1d_OBL. They should both be called using the
compute_turbulent_scales interface.