Library duplicate reactions not of Arrhenius and PDepArrhenius type

[alongd]

Loading the entire kinetic library database results in several warnings of:
Warning: Only Arrhenius and PDepArrhenius kinetics supported for duplicate reactions.
For the following libraries:

• NOx2018
• JetSurF1.0
• JetSurF2.0
• primarySulfurLibrary
• CurranPentane
• Nitrogen_Glarborg_Gimenez_et_al
• Klippenstein_Glarborg2016

This probably means that some reactions from these libraries aren't being loaded as intended by the library author/importer.

[mliu49]

I think this shouldn't have any affect on how the reactions are handled numerically. The only difference should how they're stored in objects, the difference being whether they are two reaction objects with their own kinetics, or a single reaction object with multi kinetics.

The warning comes from when we try to combine duplicate reactions into MultiArrhenius or MultiPDepArrhenius objects. As the names imply, only Arrhenius or PDepArrhenius objects are supported. There was some related discussion in ReactionMechanismGenerator/RMG-Py#1341. I think the ideal fix for this might be to create a single MultiKinetics class which could handle any kinetics type.

[mjohnson541]

Just a note, using a MultiKinetics class will probably break the current codes used to output RMG objects as RMS yaml.