SelectRows: Index attrs only by visible in set_data

In `set_data` we calculate the index of an attribute that is passed to `add_rows`. Since `add_rows` only consider visible attributes the index has to be calculated only on visible as well.

Otherwise this caused `attr_combo.setCurrentIndex` to be set to values larger than the number of items inside it. Strangely this works but causes `attr_combo.currentText()` to returns an empty string which of course breaks indexing on domain.

Orange/widgets/data/owselectrows.py

@@ -319,7 +319,7 @@ def set_data(self, data):
         self.update_info(data, self.data_in_variables, "In: ")
         for attr, cond_type, cond_value in self.conditions:
             attrs = [a.name for a in
-                     data.domain.variables + data.domain.metas]
+                     filter_visible(chain(data.domain.variables, data.domain.metas))]
             if attr in attrs:
                 self.add_row(attrs.index(attr), cond_type, cond_value)
         self.unconditional_commit()