Mechanic fixing.

Created by: ComicIronic

PDA device analysers now work as expected. Groundwork for fabricators ignoring design requirements, which general fabricators now do for chems. Item designs based on existing designs now properly generate a plastic requirement. Sped up the flatpacker a little to balance its costs. FIxes #1895 (closed), #2214 (closed). #2055 (closed) can also be closed because of the previous PR.