Detailed HVAC Viewer - add capability to show HXs on the outdoor air side of the OA mixer

[kentakahas]

• add HX to HVAC loop in test file
• add objects between relief/oa node and oa system to schema
• add capability to draw hx and outdoor objects to html

[kentakahas]

Added the capability to add a HX but the measure is not outputting the node values of the outdoor/relief air stream into the json file