If uscan fails (e.g. because there is no new version available
because the workspace is in a dirty state) we now output an error
message instead of silently failing.
This change switches the package version number for packages that
are intended for the Debian package repo to match the Debian policies.
It also removes the comment from the watch file.
This is a cherry-pick of PR#4223:
- Add script to create debian source package
- Update debian metadata based on Debian repos
- Remove some lintian warnings and errors
- Remove support Xenial
- Reduce size of icon
- Omit confusing values from gbp.conf
