force fruit name to be singular (trunk only)

Inventory formatting for a single slime mold object would be strange
if the user entered a plural word or phrase for fruit name.  Forcing the
user-specified value to be singular as it's being set up as current fruit
avoids that.  [Something like <Someone>'s "bunch of grapes" is unaffected;
it's already singular and correctly handled as such by makesingular().]
This may have a side-effect of limiting the creativity of some players
who try to trick others via bones files gimickery, but I think the extra
consistency in object naming during ordinary play is worth it.

     According to the cvs log info, this issue was actually mentioned in
a patch I made ("fix M203...") in October, 2005.  I have no recollection
of that at all....

doc/fixes35.0

@@ -94,8 +94,7 @@ mind flayer brain eating is subject to certain fatal targets and to cannibalism
 mind flayer can't eat brains of ghost or shade
 corpses of unique monsters in bones behaved incorrectly if revived or eaten
 fix pluralization for "this tin smells like mother-in-laws" when hallucinating
-try harder to keep pluralization straight when user assigns an already plural
-	value for named fruit
+force user-specified fruit name to be singular
 avoid false matches when looking up fruit names ("grapefruit" isn't "grape")
 handle pluralization of man-at-arms and singularization of men-at-arms
 assigning an artifact name is rejected on objects with similar description to