This switches the repository to be buildable using multiple versions of OCaml, in a manner similar to that used by Merlin and other compiler-dependent tools.
As a result, we can release a single ppx_tools package for multiple compiler versions. This in turn makes it much easier to use ppx_tools in dune monorepos, which makes life easier for benchmarking systems such as Sandmark used in multicore OCaml.
This switches the repository to be buildable using multiple versions of OCaml, in a manner similar to that used by Merlin and other compiler-dependent tools.
As a result, we can release a single ppx_tools package for multiple compiler versions. This in turn makes it much easier to use ppx_tools in dune monorepos, which makes life easier for benchmarking systems such as Sandmark used in multicore OCaml.
This PR applies over #82 and #84