* Added utility to make non-parametric Arch component
* Ability for all Arch components to be a clone of another Arch component of same type
* Modified the Draft Clone tool to produce Arch Clones if applicable
* Fixed Arch Roofs so they can be based on a solid shape like other Arch objects
* Ability to change the Root element to be imported in IFC preferences
* Ability to import IFC files also as compounds, Part shapes or non-parametric Arch objects
* Added an "only" parameter to importIFC.open() to import only a certain object ID.
* Ability to read colors (IfcSurfaceStyle) from IFC objects
Squashed following commits:
* Arch: Adapted IFC importer for IfcOpenShell6
* Arch: further fixes for ifcopenshell6 compatibility
* Arch: IFC importer now converts to/from meters for better compatibility with IfcOpenShell
* Arch: further fixes with ifcopenshell6
* Arch: precision adjustments in IFC exporter
* Arch: small fix in makeRoof
+ Walls can now be capped by roofs, by subtracting a roof from them
+ Walls and Structs with height = 0 take height from their parent floor
+ Changing the placement of a floor changes all the placements of its children
