Major progress on Gradle port

Complete:
--------
- src/* documentation resources moved to 'docs' subproject

- docbook sources upgraded to Docbook 5

- formatted all docbook sources to strip tab characters and
  eliminate trailing whitespace

- all projects compile and test successfully

- all artifacts upload successfully to s3, static.sf.org, etc.

Remaining:
---------
- documentation L&F needs work. CSS, images, and highlighting aren't
  hooked up properly

- spring-integration-jdbc codegen bits in Maven POM need to be
  transcribed into gradle

- dependencies that were optional or provided scope in maven are
  currently 'compile' scope in Gradle.  Need to figure out support
  in Gradle to fix this.

- run through Eclipse classpath and project generation scenarios

- delete all Maven artifacts

docs/src/reference/docbook/index.xml

@@ -0,0 +1,98 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<book xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="spring-integration-reference"
+    xmlns:xi="http://www.w3.org/2001/XInclude"
+    xmlns:xlink="http://www.w3.org/1999/xlink">
+  <bookinfo>
+    <title>Spring Integration Reference Manual</title>
+    <titleabbrev>Spring Integration ${version}</titleabbrev>
+    <productname>Spring Integration</productname>
+    <releaseinfo>${version}</releaseinfo>
+
+    <!-- TODO: this isn't showing up. -->
+    <mediaobject>
+      <imageobject role="fo">
+        <imagedata fileref="images/logo.png"
+          format="PNG" align="center"/>
+      </imageobject>
+      <imageobject role="html">
+        <imagedata fileref="images/logo.png" format="PNG" align="center"/>
+      </imageobject>
+    </mediaobject>
+    <!-- END TODO -->
+
+    <authorgroup>
+      <author>
+        <firstname>Mark</firstname>
+        <surname>Fisher</surname>
+      </author>
+      <author>
+        <firstname>Marius</firstname>
+        <surname>Bogoevici</surname>
+      </author>
+      <author>
+        <firstname>Iwein</firstname>
+        <surname>Fuld</surname>
+      </author>
+        <author>
+        <firstname>Jonas</firstname>
+        <surname>Partner</surname>
+      </author>
+      <author>
+        <firstname>Oleg</firstname>
+        <surname>Zhurakousky</surname>
+      </author>
+      <author>
+        <firstname>Gary</firstname>
+        <surname>Russell</surname>
+      </author>
+      <author>
+        <firstname>Josh</firstname>
+        <surname>Long</surname>
+      </author>
+    </authorgroup>
+
+    <legalnotice><para>© SpringSource Inc., 2010</para></legalnotice>
+  </bookinfo>
+
+  <toc></toc>
+
+  <xi:include href="./overview.xml"/>
+  <xi:include href="./message.xml"/>
+  <xi:include href="./channel.xml"/>
+  <xi:include href="./endpoint.xml"/>
+  <xi:include href="./service-activator.xml"/>
+  <xi:include href="./channel-adapter.xml"/>
+  <xi:include href="./router.xml"/>
+  <xi:include href="./filter.xml"/>
+  <xi:include href="./transformer.xml"/>
+  <xi:include href="./splitter.xml"/>
+  <xi:include href="./aggregator.xml"/>
+  <xi:include href="./resequencer.xml"/>
+  <xi:include href="./delayer.xml"/>
+  <xi:include href="./chain.xml"/>
+  <xi:include href="./bridge.xml"/>
+  <xi:include href="./gateway.xml"/>
+  <xi:include href="./message-publishing.xml"/>
+  <xi:include href="./transactions.xml"/>
+  <xi:include href="./message-history.xml"/>
+  <xi:include href="./file.xml"/> 
+  <xi:include href="./jdbc.xml"/>
+  <xi:include href="./jms.xml"/>
+  <xi:include href="./ws.xml"/>
+  <xi:include href="./rmi.xml"/>
+  <xi:include href="./httpinvoker.xml"/> 
+  <xi:include href="./http.xml"/>
+  <xi:include href="./ip.xml"/>
+  <xi:include href="./mail.xml"/>
+  <xi:include href="./jmx.xml"/>
+  <xi:include href="./xmpp.xml"/>
+  <xi:include href="./stream.xml"/>
+  <xi:include href="./event.xml"/> 
+  <xi:include href="./xml.xml"/>
+  <xi:include href="./security.xml"/>
+  <xi:include href="./groovy.xml"/>
+  <!--<xi:include href="./samples.xml"/>-->
+  <xi:include href="./configuration.xml"/>
+  <xi:include href="./resources.xml"/>
+
+</book>