Sunsword's #invoke for blinding ray

Support aiming at self (to become blinded) and aiming up/down (to
light the hero's current map spot only, persistently rather than
temporarily).  Also, recognize cancel at the "direction?" prompt to
not leave the #invoke cooldown count set when aborted.

Aiming at self was a little trickier than expected to test because
you're blindness-resistant when wielding Sunsword.  But it doesn't
have to be wielded to be invoked.

src/zap.c

@@ -2958,9 +2958,9 @@ lightdamage(
            of death will always be "killed while stuck in creature form"] */
         if (obj->oclass == SCROLL_CLASS || obj->oclass == SPBOOK_CLASS)
             ordinary = FALSE; /* say blasted rather than zapped */
-        how = (obj->oclass != SPBOOK_CLASS)
-                  ? (const char *) ansimpleoname(obj)
-                  : "spell of light";
+        how = (obj->oclass == SPBOOK_CLASS) ? "spell of light"
+              : (!obj->oartifact) ? ansimpleoname(obj)
+                : bare_artifactname(obj);
         Sprintf(buf, "%s %sself with %s", ordinary ? "zapped" : "blasted",
                 uhim(), how);
         /* might rehumanize(); could be fatal, but only for Unchanging */