Correction of an error on the temperature to take for the specific enthalpy calculation in the 'flowPort_b.H_flow' calculation

Correction in the calculation of enthalpies. The media can have different reference conditions for the calculation of the specific enthalpies and different ways to compute the latent heat. Therefore each medium should computes their enthalpies with their own functions.

-> Change the function to compute the stable to be density temperature explicit
-> The pressure of the fluidport (ie the pressure of the liquid) is supplied by the pressure of the above atmosphere (issue #12)

Correction in the velocity calculation to be in adequation with the theoretical note where the flow regime of bubbles is assumed turbulent

Modification of the module to model the boiling + errors correction on the heat flow through the flow port