`#ifdef` out special support for Pair, Vec, and Tree
comment about pair & tree removal
align code
CastCat
Typeable Tree
Circuit overhaul. Compiles.
CoerceCat
CoerceCat
remove CastCat (now CoerceCat in Category)
RepCat
repr/abst
HasRep
Switch from a' ~ Rep a to Rep a ~ a' for easier construction
comments
back to one-step HasRep
Rep (Sum a)
WrapRep for Sum, Product, All, Any
Make ap' non-local
HasRep Nat instances