Function stairFlightOutline

stairFlightOutline(
    risers: number,
    riser: number,
    tread: number,
    waist?: number,
): [number, number][]
The flight's side outline in (run, rise) coordinates, native units: the stepped top, then the underside. Counter-clockwise.
Parameters
- risers: number
- riser: number
- tread: number
- Optionalwaist: number
Returns [number, number][]