Proposals for changes in contribution principles

See:
 - https://github.com/lra/mackup/pull/405
 - https://github.com/lra/mackup/pull/153
 - https://github.com/lra/mackup/pull/175
 - https://github.com/lra/mackup/pull/127
 - https://github.com/lra/mackup/issues/367