Soundness check

[Stevendeo]

When filtering on a benchmark, it would be nice to clearly see unsoundness's, i.e. cases where the expected result is A (SAT or UNSAT) and the solver returns ~A. For alt-ergo it is easy to get ; as it cannot return SAT, one can just filter with result = unsat and expected = sat but in the future, we would also like to display as well result = sat and expected = unsat