Finishing porting Erlang tests

[seliopou]

The decision diagram tests in lib_test/test_logic.ml contain commented out tests from the Erlang project. Some will not be applicable to the OCaml version, in which case they should be deleted from the file. However the majority of them should be ported over to OCaml and become part of the test suite.

[tmcgilchrist]

The 2 Haskell implementations have tests of varying quality that might be interesting to look at;
webcrank.hs and airship.

[tmcgilchrist]

I'm working on converting the tests and implementing some of the missing parts here. It's not quite ready yet.