De-duplicate illumination instructions between upright and inverted
The upright microscope illumination is rebuilt to be based on the normal illumination for the inverted microscope in !316 (merged).
Comment !316 (comment 1259636517) suggests further de-duplication in the instructions. This would make things easier to keep up-to-date, but is not particularly simple in that case.
De-duplication would be useful at some point.