Add "unitType" field to MD2D model metadata
Units definition for the default MD2D units
Units definition for translated MKS units
Fix units comment in md2d engine
Fix small error in macroscopic-units doc
PropertyDescription class
Use PropertyDescription class
Update interactives for PropertyDescription
default formats for model properties
model.format method (uses PropertyDescription)
UnitsTranslation class
Multiple unitDefinitions
Pass properties thru units translation
Update tests' expected JSON for unitsScheme prop
Simple Ball Drop uses MKS units
Fix FPS calc (rm dependence on scale of time unit)