inventory 5.x-2.x-dev

From CVS commit:

#253585 by quimrovira: Cleaner implementation of this patch, which adds:
- Items from SQL query (inherently dangerous, be warned!)
- Items from content types (implementing feature request #128623 by ray007)
- Skip-Empty formatter
- TextField widget for arbitrary values (implementing feature request #228631 from aexl)
- Range validation on submit
- Change from name-to-value relation to itemkey-to-value and itemkey-to-name (Be careful, since this implies changing the database table {inventory_items} renaming the "name" column to "itemkey")