In examples/README, it mentions of exmaples/zenon -- certification of Tom's output using zenon and Coq. Apparently, the "zvtov" tool required for that is part of FoCaLize. Given that Coq was used to create a surveyable proof of 4-color problem, it sounds impressive.
FoCaLize -- http://focalize.inria.fr/
Coq -- http://coq.inria.fr/