Revert "Speed up Arbitrary instances slightly for DoCostCentres et al."
Revert "Speed up Arbitrary instances slightly for DoCostCentres et al."

This reverts commit 25e5e5ce9f7ec1ac88fef533fbee65f1406ea358.

It turns out that the Enum instances for DoCostCentres et al. are
not what I expected them to be. Ouch.

RyanGlScott/text-show