Update item_names.csv

Italian names BW2 items
Merge pull request #100 from valepert/patch-3

Merge valepert's Italian names for B/W 2 items. #100
Dynamically mangle long table names for Oracle; Unicode → UnicodeText.
Sort out all the non-nullable columns with empty values.
General code tidying for this Oracle fix.
Merge branch 'oracle'. #109
Update the docstring on rewrite_long_table_names.
Correct the descriptions for the Razor Claw and Razor Fang.
Add Diancie.
Load/dump dance.
Add Hold Back and Diamond Storm.
Sync moves with Showdown. #116
Fix Diamond Storm's type.
Add Diancie to the Undiscovered egg group.
Improve effects for new moves and abilities a little.
Add national dex #, dex entries, name for Diancie.
Add Spanish and Italian Pokémon names.

We decided a while back to just give up and include these separately,
even though they're really just the English names.  Now I actually need
them, because genus.
Add a separate fucking language for kanji.
Add everything remaining from the spreadsheet.
Add zero-width space to Thick Fat's flavour text as needed.