[pkg] various debian packaging fixes
- stop using *.install.in files, just use wildcards in *.install
- switch to X-Python-Version (preferred for dh_python2)
- also call dh_python2 for /usr/share/cubicweb, not just public modules
- drop long obsolete ginco and erudi migration code from cubicweb-ctl.postinst
- fix cubicweb-ctl cleanup: purge code belongs in postrm, not prerm
- don't compress changelog.html
Add some entities
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As manager, you can access to entity creation forms by using the `site management`_ page.
.. _`site management`: ../manage
As regular user, the index page or the action box may propose some links to create entities according to the context.