Fix arrow_signs warnings

mods/arrow_signs/init.lua

@@ -23,9 +23,9 @@ arrow_signs={}
 		print((sender:get_player_name() or "").." wrote \""..fields.text..
 				"\" to sign at "..minetest.pos_to_string(pos))
 		meta:set_string("text", fields.text)
-		text = arrow_signs:create_lines(fields.text)
+		local text = arrow_signs:create_lines(fields.text)
 		meta:set_string("infotext", text)
-		i=0
+		local i=0
 		for wort in text:gfind("\n") do
 		i=i+1
         end