Dune build

Things to do before this can be merged:

Blocker:

• Make CI work
• Make timing runner in CI work
• Check that CI that tests against iris master still works
• Figure out the right command to build examples in RefinedC repo
  • make && make install && refinedc check example.c: Probably suboptimal?
  • dune exec -- refinedc check --no-build example.c && dune build: Rebuilds everything
  • dune exec -- refinedc check --no-build example.c && dune build $(dirname example.c): Does this work? No
  • Can one add an option to print output_dir?
• Figure out if one can get rid of the dune files in the directories. Probably not...
• Can manual proof files live in a different folder than the generated files? - Seems very hard because dune does not allow cycles between modules
• Is there a way to write a .gitignore file that ignores all generated files? Ignore code.v, spec.v and proof_*.v
• Rename +rc+ to something else
  • proof? rc?
• Make all generated files start with rc_?

Nice to have but not important for first version:

• Make path where generated files land configurable
  • Minimal version: Allow user to pick a different directory name than +rc+
  • Advanced version: Allow the user to give a path where the generates files should live
    • if the path starts with /, it is relative to the root of the repo, otherwise it is relative to the dir of the file
    • the path can contain {FILENAME} which gets replaced by the filename of the generated file
    • examples:
      • +rc+/{FILENAME}/ current version
      • /generated/{FILENAME}_ (note no trailing slash) all generated files land in the generated folder
• Display the running time after compiling a file (similar to TIMED=y make)

Also nice to have, but not so important:

• Display a message when dune starts running a command (compared to only when the command is done)