add warning level option on the command line

created merge request !10 (merged) to address this issue

By Dominique Marcadet on 2019-04-25T01:32:32 (imported from GitLab project)

mentioned in merge request !10 (merged)

By Dominique Marcadet on 2019-04-25T01:32:33 (imported from GitLab project)

closed via merge request !10 (merged)

By Dominique Marcadet on 2019-04-30T07:14:00 (imported from GitLab project)

mentioned in commit 1047212f

By Dominique Marcadet on 2019-04-30T07:14:00 (imported from GitLab project)