add utils, use luajit which seems faster

day04/part2.lua

@@ -1,15 +1,4 @@
-function split(text, sep)
-	local parts = {}
-	local start = 0
-	local from, to = text:find(sep)
-	while from ~= nil do
-		table.insert(parts, text:sub(start, from - 1))
-		text = text:sub(to + 1)
-		from, to = text:find(sep)
-	end
-	table.insert(parts, text)
-	return parts
-end
+require("utils")
 
 local f = io.open(arg[3])
 local numbers = split(f:read("*l"), ",")