Use item subtypes - step 1
See also #334.
- The subtypes should be created by the installation wizard.
- The other wizards should set the subtype on new items but should not use subtypes for filtering
#334 is the seconds step, which add support for using subtype when searching for items. But before this can be implemented all pre-2.0 items should be updated with a subtype. The easiest way is probably to do this with the help of the table exporter and batch importers.