Add parallel flow to x2 in KIM-FP #37
Description
Add the parallel fluid velocity to the x2 parameter of the FP model. This term appears if the equilibrium Maxwellian is considered drifting, as is the case in KiLCA.
This means that
$$
x_2 = - \frac{\omega_E + k_\parallel V_\parallel}{\nu}.
$$
The parallel flow velocity is a sum of the toroidal and poloidal contributions. However, the poloidal part, which is calculated within neoclassical theory (NEO-2), can be neglected.