Forcefield: Remove deprecated update_map() call (#467)

Lejo

2018-12-09 aa82fa1d1379ca2adc552a5e90cfa9a77da3edd6

 technic/machines/LV/extractor.lua

@@ -4,7 +4,7 @@
minetest.register_craft({
   output = 'technic:lv_extractor',
   recipe = {
      {'technic:treetap', 'technic:motor',          'technic:treetap'},
      {'technic:treetap', 'basic_materials:motor',          'technic:treetap'},
      {'technic:treetap', 'technic:machine_casing', 'technic:treetap'},
      {'',                'technic:lv_cable',       ''},
   }