Merge branch 'develop' into feature/language

packages/CLI11/.appveyor.yml

packages/CLI11/.ci/azure-build.yml

packages/CLI11/.ci/azure-cmake.yml

packages/CLI11/.ci/azure-steps.yml

packages/CLI11/.ci/azure-test.yml

packages/CLI11/.ci/build_docs.sh

packages/CLI11/.ci/check_tidy.sh

packages/CLI11/.ci/make_and_test.sh

packages/CLI11/.editorconfig

packages/CLI11/.gitignore

packages/CLI11/.gitrepo

packages/CLI11/.travis.yml

packages/CLI11/CHANGELOG.md

packages/CLI11/CMakeLists.txt

packages/CLI11/LICENSE

packages/CLI11/README.md

packages/CLI11/azure-pipelines.yml

packages/CLI11/book/.gitignore

packages/CLI11/book/README.md

packages/CLI11/book/SUMMARY.md