Move weather mods to ENVIRONMENT modpack

mods/ENVIRONMENT/weather_pack/thunder.lua

@@ -0,0 +1,37 @@
+-- turn off lightning mod 'auto mode'
+lightning.auto = false
+
+thunder = {
+  next_strike = 0,
+  min_delay = 3,
+  max_delay = 12,
+}
+
+minetest.register_globalstep(function(dtime)
+  if weather.state ~= "thunder" then 
+    return false
+  end
+  
+  rain.make_weather()
+  
+  if (thunder.next_strike <= os.time()) then
+    lightning.strike()
+    local delay = math.random(thunder.min_delay, thunder.max_delay)
+    thunder.next_strike = os.time() + delay
+  end
+
+end)
+
+thunder.clear = function()
+  rain.clear()
+end
+
+-- register thunderstorm weather
+if weather.reg_weathers.thunder == nil then
+  weather.reg_weathers.thunder = {
+    chance = 5,
+    clear = thunder.clear,
+    min_duration = 120,
+    max_duration = 600,
+  }
+end