Define rawlen as en empty table if it is undefined

 - Minetest won't let us define something global unless it's a table.
   Shall it be so.
 - This prevents Minetest from complaining about StackTracePlus' attempt
   to define "rawlen"

init.lua

@@ -2,6 +2,12 @@ local secenv = _G
 local modname = minetest.get_current_modname()
 local sec = (minetest.setting_get('secure.enable_security') == 'true')
 local ie
+
+-- //MFF (Mg|01/07/2016 for classic#508, hg#104, sb#166, creative#68)
+if (rawget(_G, "rawlen") == nil) then
+	rawlen = {} -- That's extremely bad, but our only mean of stopping StackTracePlus from complaining about rawlen being undefined
+end
+
 if sec then
   ie = minetest.request_insecure_environment()
   if ie == nil then