TEST: first tests for interfaces.lily
TEST: first tests for interfaces.lily

* realizability or not for several LTL instances; this test is written
  in manner facilitating the addition of more cases;

* realizability of a GRSpec instance;

* raising of TypeError if one of the variables is not bool.

necozay/tulip-control,necozay/tulip-control,necozay/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,necozay/tulip-control,tulip-control/tulip-control,necozay/tulip-control,tulip-control/tulip-control