Make easier to reuse the code

Some ideas to make easier the reuse of the code by other people:

- [x] requirements.txt
- [x] `makefile` to prepare all the environment.
- [x] meet the necessary changes for the `makefile` written in [this comment](5#issuecomment-453878453).

Any idea is welcome! :)

Review the checklist in the issue and the changes described in the linked comment about the makefile. The issue does not define a remaining change or a clear completion condition, so the desired reuse improvements would need to be scoped before implementation.

Written by the indexing model from the issue text.