Retwis ported to modern Redis data types.

The example (and related documentation at redis.io) was not updated for
5 years. Redis had no sorted sets and hashes when the original code was
written (!). An update was really needed.

We also use a modern PHP client now: Predis. A copy is shipped within
this repository to make life easier to newcomers trying Redis for the
first time via this example.

index.php

@@ -0,0 +1,12 @@
+<?
+include("retwis.php");
+
+if (!isLoggedIn()) {
+    include("header.php");
+    include("welcome.php");
+    include("footer.php");
+} else {
+    header("Location:home.php");
+    exit;
+}
+?>