Most monsters no longer deathdrop comestibles other than their corpse

Playtesting has shown that there is too much permafood in the game
at present: in the late-game the only food-related problem is how
much to carry in order to avoid burdening yourself. In the early
game, food could previously have been a problem prior to
Minetown/Sokoban (thus the recent commit to add a guaranteed ration
in the upper dungeons), but past that point, there is easily enough
food generated on the ground. Additionally, the recent commits to
make healing sources more available in the early game reduce the
amount of time that needs to be spent waiting to heal, thus
further reducing food requirements.

The main purposes of food as a mechanic are to given an incentive
to press onwards and to discourage grinding. However, if monsters
are deathdropping non-corpse permafood, then beyond the very
early game, grinding actually generates more food than it uses up,
so the nutrition mechanic doesn't do its job properly.

Playtesting (including a full ascension!) has shown that there is
still plenty of food available even without deathdrops available
(my test game had 8 spare non-deathdrop food rations upon reaching
the Castle, at which point nutrition is no longer an issue due to
the Castle food stores and the huge numbers of C- and K-rations
dropped by the soldiers). I will address the potential problems
this causes for vegetarian Monks in a future commit.

doc/fixes3-7-0.txt

@@ -1302,6 +1302,9 @@ early dungeon (pre-Sokoban) generates extra useful survivability items
 potion of healing is much more common, and has a unique price
 alchemy may affect only a portion of the dipped potions if a large
 	stack is dipped (especially if that stack is diluted)
+monster kills can no longer deathdrop comestibles (other than the
+	monster's corpse) unless the monster collects food or
+	generates with food
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

src/mon.c

@@ -3285,7 +3285,15 @@ xkilled(
             otmp = mkobj(RANDOM_CLASS, TRUE);
             /* don't create large objects from small monsters */
             otyp = otmp->otyp;
-            if (mdat->msize < MZ_HUMAN && otyp != FIGURINE
+            if (otmp->oclass == FOOD_CLASS && !(mdat->mflags2 & M2_COLLECT) &&
+                !otmp->oartifact) {
+                /* don't drop newly created permafood from kills, unless
+                   the monster collects food; it creates too much nutrition
+                   in the late game and encourages grinding in the early
+                   game; oartifact check is paranoia and will be redundant
+                   until an artifact comestible is added */
+                delobj(otmp);
+            } else if (mdat->msize < MZ_HUMAN && otyp != FIGURINE
                 /* oc_big is also oc_bimanual and oc_bulky */
                 && (otmp->owt > 30 || objects[otyp].oc_big)) {
                 if (otmp->oartifact) /* un-create */