Stairs are not supported

[brunopostle]

The previous Perl version of the add-on supported stairs. This functionality was never migrated, though it does identify vertical stacks of stair spaces and omits floors between them.

The stair spaces need to identify door locations (where stair runs need to have horizontal landings), and draw stair objects following the perimeter of the space using code-compliant riser/going and winders. Handrails, nosing, spindles etc... should be stylable