``ChFarthestCircle`` doesn't do anything?!

[d-krupke]

ChFarthestCircle seems just to inherit from FarthestCircle without doing anything.

ChFarthestCircle::ChFarthestCircle(bool simplify, size_t num_threads)
    : FarthestCircle(simplify, num_threads) {}

Isn't convex hull stuff not implemented via rules anyways?

[d-krupke]

Removed.