2013-10-01 blanchet 2013-10-01 refactoring -- splitting between constructor sugar dependencies and true BNF dependencies
2013-09-12 traytel 2013-09-12 removed unused/inlinable theorems
2013-05-07 traytel 2013-05-07 got rid of the set based relator---use (binary) predicate based relator instead
2012-09-21 blanchet 2012-09-21 renamed "Codatatype" directory "BNF" (and corresponding session) -- this opens the door to no-nonsense session names like "HOL-BNF-LFP"