add utils, use luajit which seems faster

utils.lua

@@ -0,0 +1,19 @@
+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
+
+function sign(n)
+	if n == 0 then return 0
+	elseif n < 0 then return -1
+	else return 1
+	end
+end