compositionalflash.hh: iterate saturation and pressure within flash
concentrationFlash2p2c gets both phase pressures as input. Since the saturation is unknown, one of these pressures (more precisely, the capillary pressure) is unknown, too. In the code the pressure is iterated outside of the flash, e.g., in the routine that updates the secondary variables, and the flash is called several times during that iteration. This is not consistent with the implicit code, in my opinion, and also not very convenient. The flash should take care of iterating saturation and pressure, in my opinion.