Support pyfa's empty slot.

This simple change checks the line item against the blacklist after lowercasing it. EFT uses all lowercases (`[empty high slot]`), while pyfa does not (`[Empty High slot]`). Lowercasing the line before the comparison adds a layer for normalcy between these applications and any other application that generates EFT fits without thought of capitalization.

Additionally, I added 'empty subsystem' blacklist item. It's rare to copy a t3 fit without a subsystem, but both EFT and pyfa allow it and thus it should be supported.