Update the Eliom ecosystem to 2016-01

[FlorentBecker]

Motivation for this change

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • OS X
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

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[mention-bot]

By analyzing the blame information on this pull request, we identified @vbgl, @nbp and @ericbmerritt to be potential reviewers

[vbgl]

bsd2 might be more accurate. See https://github.com/aantron/markup.ml/blob/master/doc/LICENSE#L1

[vbgl]

I believe that the claim in your last commit does not hold: eliom can work without PPX and with OCaml-4.01. That being said, I am not convinced that maintaining two eliom configurations (with and without PPX) is worth the trouble; so enabling eliom only on 4.02 may be the right choice.

Edit: after looking a little bit further, it seems easy to build eliom without PPX support. Here is the pre-configure hook that I tested in the eliom derivation. It builds fine (with ocaml-4.01); I did not test that eliom works well.

preConfigure = stdenv.lib.optionalString (!stdenv.lib.versionAtLeast ocamlVersion "4.02") ''
      export PPX=false
    '';