Issue description:

Not enough filter slots in Importers/Exporters.

What happens:

We used to have the feature of putting a Filter (item) inside the Filter slots of Importers/Exporters. This allowed more filtering options to optimize interactions between networks when "Priority" alone wasn't enough. But this feature was removed in 1.6.x. Requiring several Importers/Exporters on a single block to increase Filter slots, making it very inefficient.

Please consider re-enabling this feature.
Thank you very much.

Version:

• Refined Storage: 1.6.x