CI - separate jobs for building and testing

See merge request adacore/colibri!44

Build adjustments

See merge request adacore/colibri!43

Cleanup build scripts and git repository

See merge request adacore/colibri!42

- Use a more recent version of opam to install ocplib-simplex 0.5
- Remove tests_with_recompilation for now (we need to discuss this)

- use a common function to run different test suites
- also tell git to ignore generated log files

- Downgrade to tcl 8.5.2 (from 8.5.9) due probably to interface
problems with newer version (to check and fix later)

- Fix simplex_ocaml for ocplib-simplex 0.5

Fixes

See merge request adacore/colibri!41

Improve mod div abs relationship

See merge request adacore/colibri!40

Fixes #59

Closes #59

See merge request adacore/colibri!39