[pkg] Properly export data files in setup.py and adjust "newcube" test With the new package layout (everything under "cubicweb" package), the custom install_lib rule which makes use of include_dirs defined in __pkginfo__.py did not prepend the package name to source directories to be copied. Fixing this. Also, in setup.py's export() function, the destination directories' path to be created during source tree walk was wrong. All this makes cubicweb/skeleton directory (which is not a package) properly installed by setup.py. The test in cubicweb/devtools/test/unittest_devctl.py wasn't properly implemented because it used an installation of cubicweb in "develop" mode which shadows such packaging issues. Also it used "python -m cubicweb" instead of directly "cubicweb-ctl" and the former appears to fall back to using the cubicweb package *from sources* instead of the installed one. Now that this test runs against the installed version of cubicweb, fix MANIFEST.in to include tox.ini files (cubicweb's and skeleton's) as this is expected from the test. Closes #14127941.

^build$
^dist$
\.egg-info$
^.tox$
^.cache$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/cubes/.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/