Allow simulating whole SFA/MF buildings

[shorowit]

Pull Request Description

Closes #1376. Closes #1450 and closes #1492.

If an HPXML file is submitted where there are multiple Building elements, each representing an individual dwelling unit, you can now tell OS-HPXML that you want to run ALL units, which creates a single combined OS/E+ model. The ability to just run one of the Building IDs is also still available.

Also allows dwelling unit multipliers via BuildingConstruction/NumberofUnits (as described here) for runtime performance reasons. When provided, simulation outputs will reflect this multiplier. When modeling individual dwelling units, there isn't that much of a benefit since all the OS-HPXML outputs could simply be multiplied by this value by the end user/software during a post-processing. But when modeling whole SFA/MF buildings, different units in the building may have different multipliers, so it cannot be performed during a post-processing step.

Breaking change: Multiple elements move from SoftwareInfo/extension to BuildingDetails/BuildingSummary/extension to allow variation across MF dwelling units:
- HVACSizingControl
- ShadingControl
- SchedulesFilePath
- NaturalVentilationAvailabilityDaysperWeek

Finally, the HPXML class has been updated to support multiple buildings. Previously:

hpxml = HPXML.new(...)
hpxml.windows.each do |window|
   ...
end

Now it will look like:

hpxml = HPXML.new(...)
hpxml_bldg = hpxml.buildings[0]
hpxml_bldg.windows.each do |window|
   ...
end

TODO:

• Update HPXML class to support multiple Buildings. Follow this example.
• Update code so that in.xml echoes the entire HPXML.
• Update ReportSimOutput measure where code uses the HPXML object
• Add simulation tests for NumberofUnits=X (compare results (annual and timeseries) to NumberofUnits=1)
• Provide a warning when unit multipliers used
• Add error-checking if OSM unique objects differ across unit models
• Improve docs
• Address FIXMEs
• Add base-multiple-units.xml sample file

Checklist

PR Author: Check these when they're done. Not all may apply. strikethrough and check any that do not apply.

PR Reviewer: Verify each has been completed.

• Schematron validator (EPvalidator.xml) has been updated
• Sample files have been added/updated (via tasks.rb)
• Tests have been added/updated (e.g., HPXMLtoOpenStudio/tests and/or workflow/tests/hpxml_translator_test.rb)
• Documentation has been updated
• Changelog has been updated
• openstudio tasks.rb update_measures has been run
• No unexpected changes to simulation results of sample files