Add Spring Framework integration with Tiles 3

Tiles 3 has modified packages and classes as well as additional
dependencies, notably "tiles-request-api", which is a request/response
abstraction independent of Servlet and JSP APIs.

In order to have both Tiles 2 and Tiles 3 integrations, the source for
the Tiles 3 integration is in a separate project spring-webmvc-tiles3.
The build process merges the compiled Tiles 3 integration classes into
the spring-webmvc module so in effect it contains both the Tiles 2 and
the Tiles 3 integrations.

This change originated as a pull request at spring-framework-issues:
https://github.com/SpringSource/spring-framework-issues/pull/30

And was additionally updated:
1f64be4aa5

Issue: SPR-8825

src/reference/docbook/view.xml

@@ -839,7 +839,9 @@ public String deletePet(@PathVariable int ownerId, @PathVariable int petId) {
 
     <para><emphasis>NOTE:</emphasis> This section focuses on Spring's support
     for Tiles 2 (the standalone version of Tiles, requiring Java 5+) in the
-    <literal>org.springframework.web.servlet.view.tiles2</literal> package.
+    <literal>org.springframework.web.servlet.view.tiles2</literal> package as
+    as well as Tiles 3 in the
+    <literal>org.springframework.web.servlet.view.tiles3</literal> package.
     Spring also continues to support Tiles 1.x (a.k.a. "Struts Tiles", as
     shipped with Struts 1.1+; compatible with Java 1.4) in the original
     <literal>org.springframework.web.servlet.view.tiles</literal>