[skeleton] Update Debian packaging template
Here are multiple updates to the Debian packaging template provided when
running `cubicweb-ctl newcube`:
* Switch to source format 3.0 (quilt).
* Switch to debhelper 9.
* Switch to dh-python.
* Add Python 3 packages.
* Name the binary packages `python-cubicweb-CUBENAME` and
`python3-cubicweb-CUBENAME` instead of just `cubicweb-CUBENAME` (which is
still the source package).
* Populate Depends using dh_python{2,3} support for Python requirements.
* Run test suite at build time using pytest.
* Add autopkgtest to run test suite against the installed package.
* Bump Standards-Version to 4.3.0.
[MASTER]
load-plugins=cubicweb.pylintext
ignore=__pkginfo__
[MESSAGES CONTROL]
disable = too-many-ancestors,too-many-instance-attributes,too-many-public-methods,
too-few-public-methods,too-many-arguments,import-error
[BASIC]
function-rgx = [a-z_][a-z0-9_]{2,35}$
good-names=w,_
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception
[CLASSES]
exclude-protected=_cw,_cnx,
# namedtuple public API.
_asdict,_fields,_replace,_source,_make
[FORMAT]
max-line-length=100
max-module-lines=2000