Add Gen III items and internal IDs to the database.

Add Gen III items and internal IDs to the database.

Items with the same name are considered the same.  So, for example,
Storage Key is all one item, even though there are multiple storage keys
named "Storage Key" across the generations.  As far as I know, this only
ever affects miscellaneous keys.

The Itemfinder is considered the same item as the Dowsing MCHN.  They
have the same Japanese name and do the same thing; as far as I'm
concerned, the name change is just another data change.

I wrote effects for the newly-added items very quickly.  They aren't
very good.  I'm leaving it up to whoever takes care of issue #247 to
write good ones.