The instances behind grobx.com's timings, one file each, in msolve's input
format: a line of variables, the characteristic, then the generators. The
file name ends in the characteristic: -p65521 is GF(65521), -p0 is Q.

tuning/   the tuning set, which grobx is developed against
holdout/  the holdout set, kept out of grobx's development
extra/    additional instances outside both sets
long/     instances of extra's kind that take even the fastest program hours

Sources:
- biomd, biomdcl: BioModels models, by accession, through ODEbase,
  https://odebase.org ; biomdcl adds the models' conservation laws.
- chou, curves, sdata, and sat's satlib.*: SymbolicData's IntPS collection,
  https://github.com/symbolicdata/data, commit a5cdf5366150bffba22a2c91a86a012dd23831af.
- sat-uf*, sat-uuf*: SATLIB, https://www.cs.ubc.ca/~hoos/SATLIB/ .
- phc: Jan Verschelde's PHCpack demo database.
- sian, hexapod: Groebner.jl's benchmark systems.
- rur: msolve's RUR benchmark data.
- powerflow: MATPOWER's case files.
- katsura, cyclic, eco, noon, henrion, chandra, reimer: the standard
  benchmark systems of their names.
- The other families are generated from the constructions of the
  literature, with random data where a construction asks for it.
