Follow up on disturbing buried zombies

Change 852f8e4 by requiring a minimum impact before a buried zombie
nearby will be disturbed: light, but still excluding things like
scrolls, if it's a violent impact (dropped while levitating, thrown, or
kicked), and fairly heavy if the hero is just placing the item on the
ground normally.

Moving the call out of flooreffects meant it no longer applied to
pushing boulders around, so have moverock disturb nearby zombies.  I
additionally had wake_nearby do the same thing.

Finally, I renamed check_buried_zombies (which doesn't really reflect
what it does) to disturb_buried_zombies.

src/dothrow.c

@@ -1777,9 +1777,11 @@ throwit(struct obj *obj,
         /* container contents might break;
            do so before turning ownership of gt.thrownobj over to shk
            (container_impact_dmg handles item already owned by shop) */
-        if (!IS_SOFT(levl[gb.bhitpos.x][gb.bhitpos.y].typ))
+        if (!IS_SOFT(levl[gb.bhitpos.x][gb.bhitpos.y].typ)) {
             /* <x,y> is spot where you initiated throw, not gb.bhitpos */
             container_impact_dmg(obj, u.ux, u.uy);
+            impact_disturbs_zombies(obj, TRUE);
+        }
         /* charge for items thrown out of shop;
            shk takes possession for items thrown into one */
         if ((*u.ushops || obj->unpaid) && obj != uball)