Add combinational logic and concept classes

smocore/include/concept.h

@@ -31,7 +31,8 @@ public:
 	ComparatorExpression(
 		logic::Operator &op, std::shared_ptr<Comparator> &comparator
 	)
-	:	logic::UnaryExpression(op, comparator)
+	:	logic::UnaryExpression(
+			op, std::static_pointer_cast<logic::Operand>(comparator))
 	{}
 };