Fixed: import of grounding methods.

Author: Daniel Nyga

Diff for: python3/pracmln/mln/mrf.py

@@ -41,7 +41,7 @@
 from ..logic import FirstOrderLogic
 from ..logic.common import Logic
 from ..logic.fuzzy import FuzzyLogic
-
+from .grounding import *
 
 logger = logs.getlogger(__name__)