[pkg] Specify priority “optional” instead of the obsolete “extra” Quoting Lintian, “Since Debian Policy version 4.0.1, the priority extra has been deprecated.” So let's use “optional” instead.

[pkg] Switch to Debian source format 3.0 (quilt) This forces us to base the Debian package on the source of the Python package (as produced by running `python3 setup.py sdist`). While it might seem cumbersome, this greatly reduces likelyhood of mismatch between an installation via `pip` and one using the Debian package. `dpkg-source` will also document for us what is currently in the source repository but not in the Python package. Currently the missing file are: PKG-INFO cubicweb/sobjects/test/data/cubicweb_comment/schema.py cubicweb/sobjects/test/data/cubicweb_comment/__init__.py cubicweb/sobjects/test/data/cubicweb_comment/__pkginfo__.py cubicweb/sobjects/test/data/cubicweb_card/schema.py cubicweb/sobjects/test/data/cubicweb_card/entities.py cubicweb/sobjects/test/data/cubicweb_card/__init__.py cubicweb/sobjects/test/data/cubicweb_card/__pkginfo__.py cubicweb/server/test/data-migractions/cubicweb_comment/schema.py cubicweb/server/test/data-migractions/cubicweb_comment/__init__.py cubicweb/server/test/data-migractions/cubicweb_comment/__pkginfo__.py cubicweb/server/test/data-migractions/cubicweb_localperms/schema.py cubicweb/server/test/data-migractions/cubicweb_localperms/__init__.py cubicweb/server/test/data-migractions/cubicweb_localperms/__pkginfo__.py cubicweb/server/test/data-migractions/cubicweb_basket/schema.py cubicweb/server/test/data-migractions/cubicweb_basket/__init__.py cubicweb/server/test/data-migractions/cubicweb_basket/__pkginfo__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_comment/schema.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_comment/__init__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_comment/__pkginfo__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_localperms/schema.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_localperms/__init__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_localperms/__pkginfo__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_basket/schema.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_basket/__init__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_basket/__pkginfo__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_tag/schema.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_tag/__init__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_tag/__pkginfo__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_card/schema.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_card/__init__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_card/__pkginfo__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_file/schema.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_file/__init__.py cubicweb/server/test/data-migractions/migratedapp/cubicweb_file/__pkginfo__.py cubicweb/server/test/data-migractions/cubicweb_tag/schema.py cubicweb/server/test/data-migractions/cubicweb_tag/__init__.py cubicweb/server/test/data-migractions/cubicweb_tag/__pkginfo__.py cubicweb/server/test/data-migractions/cubicweb_card/schema.py cubicweb/server/test/data-migractions/cubicweb_card/__init__.py cubicweb/server/test/data-migractions/cubicweb_card/__pkginfo__.py cubicweb/server/test/data-migractions/cubicweb_file/schema.py cubicweb/server/test/data-migractions/cubicweb_file/__init__.py cubicweb/server/test/data-migractions/cubicweb_file/__pkginfo__.py cubicweb/test/data-rewrite/cubicweb_localperms/schema.py cubicweb/test/data-rewrite/cubicweb_localperms/__init__.py cubicweb/test/data-rewrite/cubicweb_localperms/__pkginfo__.py cubicweb/test/data-rewrite/cubicweb_card/schema.py cubicweb/test/data-rewrite/cubicweb_card/entities.py cubicweb/test/data-rewrite/cubicweb_card/__init__.py cubicweb/test/data-rewrite/cubicweb_card/__pkginfo__.py The current manifest will duplicate several files that are stored as symlinks in the Mercurial repository, hence the long list of ignored files in `extend-diff-ignore`.

[debian] Update description of cubicweb-ctl* packages init scripts are no longer shipped. Avoid mentionning "start" and "stop" command which should not be used in production environments.