Make it possible to configure exposed filter operators

Hello,

Thanks for this wonderful module !

I was wondering if its possible to configure exposed operators.

Problem:
When we expose operator, all available operators are visible to users. I want only specified operators to be visible to users. For example, for a field_xyz I have following operators available:

• Is one of
• Is all of
• Is none of
• Is empty (NULL)
• Is not empty (NOT NULL)

I only want users to see follwings:

• Is one of
• Is all of
• Is none of

I don't want users to see NULL and NOT NULL operators.

It would be great if we have an option to do so.

Thanks in advance!