Missing termination time in SA if not defined in the RMG reactor

[alongd]

While it's legal to define an RMG reactor w/o a termination time, running SA (at least via the CanteraConstantTP adapter) does expect to have a run time that is taken from the reactor's termination time.

Suggestion: After an RMG run, read the chemical run time from RMG and assign it to the termination time if the latter is None