smarter bucket detection of dummy items

[nev-r]

this gun's sockets are being displayed as general instead of weapon,
because its bucket.inWeapons is not true,
because it's a dummy that belongs in the forbidden bucket.

this fake dimitem's bucket prop (which is supposed to describe where it belongs, not where it is)
could be corrected by matching name and item type against a non-dummy in the defs

[bhollis]

We have a similar name-matching thing for collections, I bet it could be reused.