Final preparations for 3.2 GA
Minor rewording
Remove previousVersion from 'jdiff' Gradle task
Upgrade reference plugin to version 0.2.4

Pick up fix for regression in version 0.2.3 that caused project-specific
images, e.g. diagrams not to be copied into the images/ folder, thereby
causing broken image links online and in the PDF.
Update "what's new" in 3.1 and 3.2 sections

 - Remove unnecessary "overview of new features" section in 3.1
 - Mention new Gradle build and GitHub-based source control in 3.2
Restore 3.2.0.RELEASE url paths in migration guide
Release version 3.2.0.RELEASE
Increment version to 3.2.1.BUILD-SNAPSHOT
Fix JavaDoc in MockRestServiceServer
Fix typo in 3.2 migration guide

- @WebApplicationContext --> @WebAppConfiguration

Backport-Commit: 62e9d6b105feffcd3b9d8b25e8661f993d703c26
Allow for SpEL expressions in initial-delay attribute

Issue: SPR-10102
Added MappingJackson2MessageConverter for JMS

Issue: SPR-10099
JmsTemplate uses configured receiveTimeout if shorter than remaining transaction timeout

Issue: SPR-10109
Fixed AbstractAutoProxyCreator to accept null bean names again

Issue: SPR-10108
Fixed QualifierAnnotationAutowireCandidateResolver's detection of custom qualifier annotations

Issue: SPR-10107
Initial preparations for 3.2.1
Fix GenericConversionService search algorithm

Previously the algorithm used by GenericConversionService to find
converters incorrectly searched for interfaces working up from the
base class. This caused particular problems with custom List
converters as as the Collection interface would be considered before
the List interface giving CollectionToObjectConverter precedence
over the custom converter.

The updated algorithm restores the class search order to behave in the
same way as Spring 3.1.

Issue: SPR-10116
Backport-Issue: SPR-10117
Backport-Commit: aa914497dc312568cc541e53302038729364ce68
Add spring-oxm-1.5.xsd

Issue: SPR-10121
Update contributor guidelines regarding 3.2.x branch
Support snapshot versions qualified by branch name