Statistics: settings are not saved

[ajdapretnar]

Describe the bug
Settings in Statistics widget are not saved.

To Reproduce
Steps to reproduce the behavior:

Option 1: set a selection of settings in Statistics. Then copy-paste the widget. The settings are reset to default when copying.
Option 2: set a selection of settings in Statistics. Save the workflow. Open it in a fresh Orange canvas. The settings are not saved.
Option 3: set a selection of settings in Statistics after Bag of words. Then remove the connection to BoW and connect directly to Preprocess Text. The necessary info for Statistics shouldn't change. However, the widget is reset to default.

Expected behavior
Settings in Statistics remain.