add Japanese item names to discoveries list

When playing as a Samurai, add things like "osaku" to the discoveries
list even though they don't have separate descriptions to be used
when not yet discovered.  Non-magic ones are pre-discovered and
players can now use the '\' command to figure out what things like
"tanko" mean without resorting to '/?'.

"wooden harp" has been getting changed to "koto (harp)"; make that be
| koto [wooden harp] (koto)
"magic harp" has been staying as "magic harp (harp)"; add it to the
list of Japanese item names.  Since it's magic it isn't pre-discovered.
Once discovered it becomes
| magic koto [magic harp] (koto)

Those two needed special case handling, none of the other items did
aside from forcing them to be discoverable when lacking descriptions.
The discoveries list now has things like
| wakizashi [short sword]
| naginata [glaive] (single-edged polearm)
| gunyoki [food ration]
if--and only if--the hero is a Samurai.

doc/fixes3-7-0.txt

@@ -1931,6 +1931,7 @@ add 'sortvanquished' option to be able to set the preferred sort order without
 	using 'm #vanquished' and to have it persist across save/restore
 have 'I u' mention whether there are any unpaid items on the floor (unusual
 	but not impossible); it doesn't itemize them or show shop price
+add items given a Japanese name when playing as a Samurai to discoveries list
 
 
 Platform- and/or Interface-Specific New Features