Issue description: In GregTech there are machines with several fluid output slots, the fluid importer can only drain from the first non-empty fluid slot.

What happens: The importer on fluid mode only imports fluids from the first slot.

What you expected to happen: That the importer can import fluid from any slot.

Steps to reproduce:

1. Using GTCE run any recipe that results in 2 or more fluids.
2. Try to import a fluid that isn't in the first slot from the left.

Basically the issue is here. It should loop over the fluid tank properties like here.

Thanks for the hint!

Thank you for the quick fix! The mod I manage, Gregicality, actually has some more coremod fixes for Refined Storage. Refined Storage can't shift click GTCE tools into crafting grid. This is our coremod for RS.

I'm not exactly sure what those hooks are supposed to accomplish, but inserting and extracting works for me with meta items.