Add a random magic marker or magic lamp to Orcustown

Part 3 of implementing wish spreading. These items are each worth
most of a wish for non-illiterate games (most games wish for a
magic marker, and a magic lamp gives a wish 80% of the time).

The placement of the random item could be better (currently it is
purely random, which is occasionally interesting but often boring),
but this will serve as a base for experimenting with the balance
properties of the moved wishes.

dat/orcus.lua

@@ -102,6 +102,13 @@ local orcus1 = des.map({ halign = "right", valign = "center", map = [[
    des.object()
    des.object()
    des.object()
+   -- An object that's worth most of a wish
+   -- (this is part of the compensation for the reduced wishes at the Castle)
+   if math.random(0, 1) == 1 then
+      des.object("magic marker")
+   else
+      des.object("magic lamp")
+   end
    -- The resident nasty
    des.monster("Orcus",33,15)
    -- And its preferred companions