- Add the new helper ynh_check_app_version_changed to check the version before an upgrade
- Add also the helpers ynh_read_manifest, ynh_app_upstream_version and ynh_app_package_version.
- These previous helper have been modified (from the experimental version) to support getopts
- ynh_check_app_version_changed has been modified to use ynh_app_upstream_version
* New helper ynh_check_error
Helpers to implemente trap and set -eu.
Simply to use, you only add `ynh_check_error` in your script.
* Change helper's name
* Propagate new name in comments