wip/spot 2.7.1 NetBSD

Spot is a library for LTL, omega-automata manipulation and model checking.

It has the following notable features: * Support for LTL (several syntaxes supported) and a subset of the linear fragment of PSL. * Support for omega-automata with arbitrary acceptance condition. * Support for transition-based acceptance (state-based acceptance is supported by a reduction to transition-based acceptance). * The automaton parser can read a stream of automata written in any of four syntaxes (HOA, never claims, LBTT, DSTAR). * Several algorithms for formula manipulation including: simplifying formulas, testing implication or equivalence, testing stutter-invariance, removing some operators by rewriting, translation to automata, testing membership to the temporal hierarchy of Manna & Pnueli... * Several algorithms for automata manipulation including: product, emptiness checks, simulation-based reductions, minimization of weak-DBA, removal of useless SCCs, acceptance-condition transformations, determinization, SAT-based minimization of deterministic automata, etc. * In addition to the C++ interface, most of its algorithms are usable via command-line tools, and via Python bindings. * One command-line tool, called ltlcross, is a rewrite of LBTT, but with support for PSL and automata with arbitrary acceptance conditions.