Sergio Ferraris authored Dec 14, 2020 and Andrew Heather committed Dec 15, 2020

The FO BilgerMixtureFraction needs access to specieComposition which is
stored in ReactingMixture. A virtual mechanism was added to
basicSpecieMixture to access specieComposition form rho and psi
reationThermos.

ptr was changed to autoPtr to avoid memory leaks (Kutalmis Bercin)