More peaceful monsters that can't be displaced: priests, Oracle

Shouldn't be able to displace priests since that could theoretically
eventually force them out of their temple, which would probably cause
problems. The Oracle doesn't usually move anyway, but seems like she
should "not want to swap places" in any circumstance.

src/hack.c

@@ -1839,9 +1839,11 @@ domove_core()
         } else if (mtmp->mpeaceful && !mtmp->mtame
                    && (!goodpos(u.ux0, u.uy0, mtmp, 0)
                        || t_at(u.ux0, u.uy0) != NULL
+                       || mtmp->ispriest
+                       || mtmp->data == &mons[PM_ORACLE]
                        || mtmp->m_id == g.quest_status.leader_m_id)) {
             /* displacing peaceful into unsafe or trapped space, or trying to
-             * displace quest leader */
+             * displace quest leader, Oracle, or priest */
             u.ux = u.ux0, u.uy = u.uy0; /* didn't move after all */
             You("stop.  %s doesn't want to swap places.",
                 upstart(y_monnam(mtmp)));