Add the tiger source code bundle from the book site

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

tiger/testcases/test3.tig

@@ -0,0 +1,8 @@
+/* a record type and a record variable */
+let
+	type  rectype = {name:string, age:int}
+	var rec1:rectype := rectype {name="Nobody", age=1000}
+in
+	rec1.name := "Somebody";
+	rec1
+end