Formats an array of items (objects, or their short strings) into a
single natural-language list — grouping identical shorts and counting
them, e.g. "two swords, a shield and some coins".
The optional arguments tune the output: `type` selects which short
(a named category) to query from the objects; `no_dollars` suppresses
the `$`-markup used for colour/where clauses; `quiet` omits items
flagged as quiet; and `dark` produces the description as seen in the
dark. This is a Discworld-mudlib inventory helper.