Parser for DIMACS CNF format

[jardinetsouffleton]

Currently, DIMACS CNF format is not supported. In this format, variables -literals- are represented as integers and their negation is represented by the opposite (-1* ). Every line contains clauses where literals are in an AND statement and different lines are connected by OR statements. Lines end with 0

-3 -1 2 6 0
2 -6 3 1 4 0
-5 -2 1 -6 -4 3 0
4 -2 -1 -3 -5 6 0
6 -3 4 1 -5 2 0