Changed the default units to joules and Pa for incompressible fluids (this might have to be changed for brines too)
Note that Psat is still in kpa (it is not used anyways).

Added the pressure dependency in the enthalpy calculation of incompressible fluids

Corrected an undefined second derivative call in the two-phase region in rho_smooth_xend

Added Therminol 66 as a new incompressible fluid

Added a EES utility to derive the correct incompressible fluid coefficients from the original equation

Jorrit can you check that I didn't make any mistake?