GetAllPossibleRoundingCombinations: get score for numbers of correct and incorrect predictions
Description
Returns all possible rounding combinations of a 2x2 table.
Given the values of n++, n+-, n-+ and n-- (stored in twoByTwoContingencyTable) this function will
compute all possibilities of rounding each value up or down.
Approximate values of n++, n+-, n-+ and n--, these values are
calculated to optimise the D-value (see page 6 of Assessing
statistical significance of causal graphs)