consistent toString functions for expressions, parentasis are added if neccessary

src/main/java/jef/expressions/TernaryExpression.java

@@ -15,6 +15,11 @@ public class TernaryExpression implements Expression {
         return Type.TERNARY;
     }
 
+    @Override
+    public Priority getPriority() {
+        return Priority.TERNARY;
+    }
+
     @Override
     public String toString() {
         return "IF(" + cond + ", " + whenTrue + ", " + whenFalse + ")";