Do not concatenate solution, preloaded, and test code

[monadius]

It should be possible to have 3 separate files: preloaded.ml, solution.ml, and tests.ml. It will be necessary to manually import preloaded code with open Preloaded (or using the Preloaded. prefix) and solution with open Solution. But all line numbers in error and warning messages will be correct for both user code and tests.

[monadius]

I think it is better to update the OCaml version (the latest version is OCaml 4.13.1; but OCaml 4.14 should be released pretty soon) and fix this issue for a new OCaml version only.

[kazk]

Yeah, I have TODO comment somewhere. It'll be a breaking change, so a new version is necessary.

[kazk]

Separate issue, but I also want to manage dependencies properly.

[monadius]

I can prepare an image for a new OCaml version. Or should I wait until OCaml 4.14 is released? I don't think there will be a big difference between OCaml 4.14 and OCaml 4.13.1.

[kazk]

Thanks! I want #3 merged first, so we can freeze 4.07 and move to 4.13.1. We don't need to wait for 4.14.

[phreppo]

OCaml 5.0.0 has been just released. Maybe it is worth updating directly to this major version.

[kazk]

Fixed in #6.
OCaml 5.0.0 will be deployed next week.