GasSolidCatalyticWall

This PR adds GasSolidCatalyticWall that is a subclass of CatalyticWallBase. This, essentially, adds the capability for wall reactions of the form of N+C(s)->CN. It's slightly different than the GasRecombinationCataltyicWall because there we just use max conservation to supply the product flux. In this case, we have to take into account the consumption of the solid on the wall. A more general version will take into account the stoichiometry, but this is a start and gets what I need for now.

The Doxygen documentation is poor; will open separate issue for that. It is regression tested though.