Unary rules

[davidweichiang]

Grammar.writeData was printing out grammars with rules that sum to more than one. This was apparently for two reasons:

• It was intentionally printing out the max-closed unary rules instead of the real unary rules. But (IMO) it should print out the real rules because it's possible to recompute the max-closed rules from the real rules but not vice versa.
• Grammar.computePairsOfUnaries had a line that was adding the sum-closed unary rules to the set of real unary rules.