Simplify some special level lua

These were generated by a script that converted the des-file
format to lua.

dat/Rog-strt.lua

@@ -157,10 +157,10 @@ des.monster({ id = "leprechaun", x=74, y=04, peaceful=0 })
 des.monster({ id = "leprechaun", x=25, y=19, peaceful=0 })
 des.monster({ id = "water nymph", x=25, y=18, peaceful=0 })
 -- Wandering the streets.
-for i=1,4 + math.random(1 - 1,1*3)  do
+for i = 1, math.random(4,7) do
    des.monster({ id = "water nymph", coord = streets:rndcoord(1), peaceful=0 })
    des.monster({ id = "leprechaun", coord = streets:rndcoord(1), peaceful=0 })
 end
-for i=1,7 + math.random(1 - 1,1*3)  do
+for i = 1, math.random(7,10) do
    des.monster({ id = "chameleon", coord = streets:rndcoord(1), peaceful=0 })
 end

dat/astral.lua

@@ -58,7 +58,7 @@ for i=1,2 do
         des.terrain(41,18, ".")
      end
      -- extra monsters; was [6 + 3d4] when both wings were opened up at once
-     for i=1,3 + math.random(2 - 1,2*3) do
+     for j = 1, math.random(4,9) do
         des.monster({ id="Angel", coord = hall:rndcoord(1), align="noalign", peaceful=0 })
         if percent(50) then
            des.monster({ coord = hall:rndcoord(1), peaceful=0 })

dat/minetn-1.lua

@@ -88,7 +88,7 @@ des.object({ id = "corpse", montype="watchman" })
 des.object({ id = "corpse", montype="watch captain" })
 
 -- Rubble!
-for i=1,9 + math.random(2 - 1,2*5) do
+for i = 1, math.random(10,19) do
   if percent(90) then
     des.object("boulder")
   end
@@ -118,7 +118,7 @@ des.object({ id = "wand of magic missile", coord = place[5], buc="uncursed", spe
 local inside = selection.floodfill(18,8)
 local near_temple = selection.area(17,8, 23,14) & inside
 
-for i=1,5 + math.random(1 - 1,1*10) do
+for i = 1, math.random(5,15) do
    if percent(50) then
       des.monster({ id = "orc-captain", coord = inside:rndcoord(1), peaceful=0 });
    else
@@ -137,7 +137,7 @@ for i=1,math.random(1,6) do
 end
 -- these are not such a big deal
 -- to run into outside the bars
-for i=1,9 + math.random(2 - 1,2*5) do
+for i = 1, math.random(10,19) do
    if percent(90) then
       des.monster({ id = "hill orc", peaceful = 0 })
    else