Izchak occasionally stocks wands/scrolls/spellbooks of light

This comes from xNetHack by copperwater <aosdict@gmail.com>

include/mkroom.h

@@ -35,7 +35,7 @@ struct shclass {
     struct itp {
         int iprob;    /* probability of an item type */
         int itype;    /* item type: if >=0 a class, if < 0 a specific item */
-    } iprobs[6];
+    } iprobs[9];
     const char *const *shknms; /* list of shopkeeper names for this type */
 };