Fix possible memory leak in newPhase
Fix possible memory leak in newPhase

If importPhase threw an exception, then the ThermoPhase object allocated here
would not be deleted. Switching to a smart pointer fixes this problem.

imitrichev/cantera,imitrichev/cantera,imitrichev/cantera,imitrichev/cantera,imitrichev/cantera,imitrichev/cantera