Merge ir and res modules
Instead of doing a real merge, the ir and res modules are setup and register together.
This avoid to have to rename all the ir and res prefix in XML while removing the need to customize ir module in res module.
The only drawback is that the administrator group (and the admin user) which are created by XML in res module need to be inserted by the init.sql (as long as their ir.model.data so the XML ref attribute can find them).