Generalise operations from GCompare to HetOrd?

[LSLeary]

heterogeneous-comparison provides HetOrd generalising GCompare.

Almost all operations on DMap k f can be generalised from GCompare k i.e. (HetOrd k, Strength k ~ Nominal) to (HetOrd k, Strength k > Phantom). This is a plain win. Only for those which explicitly require Has' constraints is there an issue of choice between (the current) (HetOrd k, Strength k ~ Nominal, Has' (Eq|Ord) k f) and (HetOrd k, Het(Eq|Ord) f). For these operations, it might make sense to provide both versions.

I don't currently have any plans to do this myself, but if the maintainers here want to make it happen, I'm happy to help.