Fix error of backguard compatibility for 0.4 due usage of core translator

* use compatibility code for intllib lib in 0.4 series
* added dependency around intllib for 0.4
* closes: https://codeberg.org/minenux/mobs_balrog/issues/2

depends.txt

@@ -0,0 +1,2 @@
+mobs
+intllib?

init.lua

@@ -41,8 +41,20 @@
 
 -- Used for localization
 
-local S = minetest.get_translator("mobs_balrog")
-
+local S, NS
+if minetest.get_translator ~= nil then
+    S = minetest.get_translator(core.get_current_modname())
+else
+    if minetest.get_modpath("intllib") then
+        local MP = minetest.get_modpath("intllib")
+        S, NS = dofile(MP.."/lib/intllib.lua")
+    else
+        S = function(str, ...)
+            local args={...}
+            return str:gsub("@%d+", function(match) return args[tonumber(match:sub(2))] end )
+        end
+    end
+end
 
 --
 -- Balrog's spawn settings