Create a basic staircase along a boundary polyline.

Input parameters:

1. Bn → Outside boundary of stairs.
2. He → Height difference between first and last step.
3. Wi → Width of staircase
4. De → Depth hint of individual steps.
5. Th → Thickness of shape underneath steps.
6. Ff → Stair flight filling method.
   • 0 → Exact
   • 1 → Approximate
7. Lf → Stair landing filling method.
   • 0 → One Step
   • 1 → Two Steps
   • 2 → Many Steps

Output parameters:

1. Sh → Staircase surface.
2. St → Steps on all flights and landings.
3. Fp → Footprint of staircase on ground.