CBECC feature merge

@macumber I'm sorry there is a lot mixed in here.

Basic areas of change are:

Allow PIU terminals to induce air through plenum - this is private (impl) only
Enhance SDD -> OSM translator - Exhaust fans, evap cooling, heat pumps, return fans, better names of objects
Allow setpoint control on AirLoopHVACUnitarysystem - private (impl) only
Allow any configuration of exhaust stream OA components.
@kbenne  Why not just model?