Disable HTML entities in e-mail subject

If you use e.g. apostrophes in the subject line of the basic cart checkout settings (.../admin/config/basic_cart/settings/checkout), they are translated as ' in the mail itself.

In .../sites/all/modules/basic_cart/basic_cart_order/basic_cart_order.module, I changed:

- $message['subject'] = t(check_plain(variable_get('basic_cart_admin_subject')));
+ $message['subject'] = t(decode_entities(filter_xss(variable_get('basic_cart_admin_subject'))));

I left the check_plain out.

I suppose the same issue exists for the user_mail.

SOURCES
- https://www.drupal.org/project/mass_contact/issues/1971386#comment-7308562
- https://drupal.stackexchange.com/questions/88419/how-do-i-stop-html-enti...