disable verbosity by default

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
fix a bug with the progression code

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
remove useless code

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
avoid recursion when there is only one element

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>