Positive CNF benchmark library

The catalogue contains positive-scope DIMACS CNF benchmark families only.
SATLIB UF and CBS instances retain their original SATLIB provenance and are not relicensed here.
The planted random families originate with Jacob Bulmash's benchmark library.
The 2,000-variable family contains seven exact positive-scope benchmark files.
Every assignment displayed by the Solver Race is independently checked against the selected formula.

SATLIB: https://www.cs.ubc.ca/~hoos/SATLIB/benchm.html