Offset a curve in a plane.

Input parameters:

1. Cr → Curve to offset.
2. Ds → Offset distance.
3. St → Offset style to use.
   • 0 → Per-Segment
   • 1 → Sharp Corners
   • 2 → Chamfer Corners
   • 3 → Round Corners
   • 4 → Smooth Corners
   • 5 → Loose
4. Cp → Cap shapes at open offset ends.
   • 0 → None
   • 1 → Flat
   • 2 → Round
5. Pl → Optional offset plane.

Output parameters:

1. Cr → Offset curve.