Fix radiation protection when armor group is not set (#509)

coil

2019-12-30 da95be53ec5703e808233d7b45fc42fb500863dd

 technic/machines/MV/wind_mill.lua

@@ -13,7 +13,7 @@
minetest.register_craft({
   output = 'technic:wind_mill',
   recipe = {
      {'',                           'technic:motor',              ''},
      {'',                           'basic_materials:motor',              ''},
      {'technic:carbon_steel_ingot', 'technic:carbon_steel_block', 'technic:carbon_steel_ingot'},
      {'',                           'technic:mv_cable',           ''},
   }