4.1
Fix type error with inheritied polymorphic variant type in [@@deriving map].
Fix incorrect handling of multi-argument constructors in [@@deriving show].
Add API hooks for ppx_type_conv.
Show, eq, ord, map, iter, fold: add support for Result.result.
Ppx_deriving.Arg: use Result.result instead of polymorphic variants.
Ppx_deriving.sanitize: parameterize over an opened module.
Add support for [@@deriving] in module type declarations.
Add support for loading findlib packages instead of just files in ppx_deriving_main.
Treat types explicitly qualified with Pervasives also as builtin.
Compatibility with statically linked ppx drivers.
