972110 swimming pool

Changes and additions needed to model indoor swimming pools; this work is ready for review
This is not a valid unit - standard units are listed at the top of the IDD.  Would be much better if this were per volume flow rate instead of mass flow - since the volume flow rate is in the field above.  That would make the units W/(m3/s).
N6 would be better named Pool Heating System Maximum Water Flow Rate.
At some point, this IDD object needs \memo and \notes, but that can happen later.