972110 swimming pool

Changes and additions needed to model indoor swimming pools; this work is ready for review
@RKStrand  Is this a surface name or construction name?  \reference does not apply here, only \object-list.  There may be multiple \object-list if needed.  If this is a construction name, then that's what the field name should be.  If it's a surface name, then it should be \object-list <relevant surface type>

I agree with @Myoldmopar that this should not make a new IDD group.  I would put it in the Internal Gains group, perhaps right after zonebaseboard:outdoortemperaturecontrolled?