fix rain not showing for freshly joined players

mods/ENVIRONMENT/mcl_weather/rain.lua

@@ -130,6 +130,12 @@ mcl_weather.rain.add_player = function(player)
 	end
 end
 
+minetest.register_on_joinplayer(function(player)
+	if mcl_weather.rain.raining then
+		mcl_weather.rain.add_player(player)
+	end
+end)
+
 -- remove player from player list effected by rain.
 -- be sure to remove sound before removing player otherwise soundhandler reference will be lost.
 mcl_weather.rain.remove_player = function(player)