0.29.0

The least concentrated optimum, the best constant, both signs of an
objective, and hypergraphs. No new commands (59) or kinds (60); the schema
stays 5.

New

• opt --diffuse: among the optimal solutions, the least possible
  largest joint load of a pair of resources, certified by the dual of a
  second program that holds the optimum -- whether a concentrated support is
  this solution's or every optimal one's.
• The best constant on a refutation: a refuted bound on one variable,
  with linear hypotheses, comes back with the constant they do give and its
  variable_range certificate (best_constant).
• HypergraphSpec (matching, transversal; JSON too) under opt, mixed --prove-optimal and cover --minimum; triangle_packing and
  triangle_cover give nu(G) and tau(G).
• cover --minimum with the LP bound and the gap, in one output.

Fixed

• A minimisation's objective, both ways: opt and the card give the
  declared value and the canonical one the certificate stores, with the sense;
  a harness read -1/8 for a minimum of 1/8. The card says exact: false
  for a valid partial certificate.
• The card no longer counts an LP's row names as hypotheses used.