Problem with wpum_sanitize_key()

Hi,

I’ve noticed that you now have a wpum_sanitize_key() function in /includes/fields/class-wpum-field.php that filters all special characters except _. The problem is that on some websites I have a script that relies on fields that contain - in their meta_key. So my question is:

Would it be possible to include the - in the regular expression? Or at least have a filter to adjust the regular expression?

Thanks for your help!