Cull points that are coincident within a tolerance.

Input parameters:

1. Pt → Point to evaluate.
2. Tl → Optional proximity tolerance distance. If omitted, the Absolute Tolerance Pin is used as a fallback.
3. Md → Culling method to apply.
   • 0 → Leave One
   • 1 → Cull All
   • 2 → Average

Output parameters:

1. Pt → Culled points.
2. Ix → Index map of culled points.
3. Oc → Number of input points represented by this output point.