Adds additional unit-of-measure (dimensionality) specifications

[dorchard]

• Give units of intermediates: irhoadz, irhoadzdz:

Analysis from the calculation of these values:

Since we have:

        != unit (kg / m**3) :: rho
        real(dp), intent(in) :: rho(:)
            !! air density at pressure levels
...
        != unit 1 :: adz
        real(dp), intent(in) :: adz(:)
            !! ratio of the pressure level grid height spacing [m] to dz (lowest dz spacing)

then

irhoadz(k) = dtn/(rho(k)*adz(k)) !  Temporary factor for below

implies that irhoadz has unit s / ((kg / m**3) * 1) = s m**3 / kg and

irhoadzdz(k) = irhoadz(k)/dz 

implies that irhoadzdz has unit s m**2 / kg

• give units of q_sed_flux (mass flux per unit area, as per my e-mailed analysis).