Fix Middle Click Swallowing on AE2 Fake Slots

[shartte]

AE2's fake slot return a non-null container because some other inventory sorting / mouse tweak mods will crash if we do.

This changes the current check that only skips slots if they have a null container to also skip slots that do have a container but that container's size is 0.

Since SlotItemHandler also uses an empty fake container and I do not know if this mod works correctly for those slots, I explicitly skip my new check for that type of slot.