refactoring item subtypes, preferences

- replaced the ammo subtype with a generic one since it doesn't have any
special data read
- moved name and initial offsets for subtypes to base class
- instead of loading only weapons/armor all items with subtypes are
loaded initially to be used with roles/preferences
- added a flagarray to item subtypes for flags like
melee/ranged/armor/clothing/etc
- cleaned up the preference flag setting/copying
add offset for tool adjective, pref searching

- allows the search in the preference dock to also filter on the
category column
- adds offset for the tool adjective item subtype to the layouts