add utils, use luajit which seems faster

prepare

@@ -5,9 +5,7 @@ part="$2"
 day="$(printf '%02d' "$day")"
 
 if test -f "day${day}/part${part}.lua"; then
-	luac -o luac.out "day${day}/part${part}.lua"
-	printf '#!/bin/sh\nlua luac.out "$@"\n' > run
-	chmod u+x run
+	luajit -v >/dev/null
 elif test -f "day${day}/part${part}.hs"; then
 	#stack build
 	stack ghc -- -O3 "day${day}/part${part}.hs" -o run