Dynamic criteria doesn't respect lookup data types

[PetrDlouhy]

It is not possible to set datatypes of the dynamic criteria lookup values. So lookups with keys like __isnull or IDs aren't working very well.

I think, that the dynamic criteria aren't very well designed. I was trying to experiment with behaviour similar to how list_filters are working in django-admin (at least if the criteria values list is blank), but I didn't figure it out yet.