y type instead of angle
    Q2   - merge all non-convex at once instead of independent sets
    Q3   - do not merge redundant vertices
    Q4   - avoid old>new merges
    Q5   - do not correct outer planes at end of qhull
    Q6   - do not pre-merge concave or coplanar facets
    Q7   - depth-first processing instead of breadth-first
    Q8   - do not process near-inside points
    Q9   - process furthest of furthest points
    Q10  - no special processing for narrow distributions
    Q11  - copy normals an