Rebuild a curve within a given tolerance.

Input parameters:

1. Cu → Curve to resample.
2. Tl → Optional allowed deviation between input and resampled curve. If omitted, the Absolute Tolerance Pin is used as a fallback.
3. Dg → Optional curve degree override.
4. Tn → If true, the tangents at the curve ends are kept.

Output parameters:

1. Cr → Resampled curve.
2. Dv → Maximum deviation between the original and the resampled curve.