Issue: SPR-14432

Prior to this commit, there was no declarative mechanism for a custom
TestExecutionListener to be registered as a default
TestExecutionListener.

This commit introduces support for discovering default
TestExecutionListener implementations via the SpringFactoriesLoader
mechanism. Specifically, the spring-test module declares all core
default TestExecutionListeners under the
org.springframework.test.context.TestExecutionListener key in its
META-INF/spring.factories properties file, and third-party frameworks
and developers can contribute to the list of default
TestExecutionListeners in the same manner.

 - AbstractTestContextBootstrapper uses the SpringFactoriesLoader to
   look up the class names of all registered default
   TestExecutionListeners and sorts the instantiated listeners using
   AnnotationAwareOrderComparator.

 - DefaultTestContextBootstrapper and WebTestContextBootstrapper now
   rely on the SpringFactoriesLoader mechanism for finding default
   TestExecutionListeners instead of hard coding fully qualified class
   names.

 - To ensure that default TestExecutionListeners are registered in the
   correct order, each can implement Ordered or declare @order.

 - AbstractTestExecutionListener and all default TestExecutionListeners
   provided by Spring now implement Ordered with appropriate values.

 - Introduced "copy constructors" in MergedContextConfiguration and
   WebMergedContextConfiguration

 - SpringFactoriesLoader now uses AnnotationAwareOrderComparator
   instead of OrderComparator.

Issue: SPR-11466

Prior to this commit the Spring TestContext Framework supported creating
only flat, non-hierarchical contexts. There was no easy way to create
contexts with parent-child relationships.

This commit addresses this issue by introducing a new @ContextHierarchy
annotation that can be used in conjunction with @ContextConfiguration
for declaring hierarchies of application contexts, either within a
single test class or within a test class hierarchy. In addition,
@DirtiesContext now supports a new 'hierarchyMode' attribute for
controlling context cache clearing for context hierarchies.

- Introduced a new @ContextHierarchy annotation.
- Introduced 'name' attribute in @ContextConfiguration.
- Introduced 'name' property in ContextConfigurationAttributes.
- TestContext is now aware of @ContextHierarchy in addition to
  @ContextConfiguration.
- Introduced findAnnotationDeclaringClassForTypes() in AnnotationUtils.
- Introduced resolveContextHierarchyAttributes() in ContextLoaderUtils.
- Introduced buildContextHierarchyMap() in ContextLoaderUtils.
- @ContextConfiguration and @ContextHierarchy may not be used as
  top-level, class-level annotations simultaneously.
- Introduced reference to the parent configuration in
  MergedContextConfiguration and WebMergedContextConfiguration.
- Introduced overloaded buildMergedContextConfiguration() methods in
  ContextLoaderUtils in order to handle context hierarchies separately
  from conventional, non-hierarchical contexts.
- Introduced hashCode() and equals() in ContextConfigurationAttributes.
- ContextLoaderUtils ensures uniqueness of @ContextConfiguration
  elements within a single @ContextHierarchy declaration.
- Introduced CacheAwareContextLoaderDelegate that can be used for
  loading contexts with transparent support for interacting with the
  context cache -- for example, for retrieving the parent application
  context in a context hierarchy.
- TestContext now delegates to CacheAwareContextLoaderDelegate for
  loading contexts.
- Introduced getParentApplicationContext() in MergedContextConfiguration
- The loadContext(MergedContextConfiguration) methods in
  AbstractGenericContextLoader and AbstractGenericWebContextLoader now
  set the parent context as appropriate.
- Introduced 'hierarchyMode' attribute in @DirtiesContext with a
  corresponding HierarchyMode enum that defines EXHAUSTIVE and
  CURRENT_LEVEL cache removal modes.
- ContextCache now internally tracks the relationships between contexts
  that make up a context hierarchy. Furthermore, when a context is
  removed, if it is part of a context hierarchy all corresponding
  contexts will be removed from the cache according to the supplied
  HierarchyMode.
- AbstractGenericWebContextLoader will set a loaded context as the
  ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE in the MockServletContext when
  context hierarchies are used if the context has no parent or if the
  context has a parent that is not a WAC.
- Where appropriate, updated Javadoc to refer to the
  ServletTestExecutionListener, which was introduced in 3.2.0.
- Updated Javadoc to avoid and/or suppress warnings in spring-test.
- Suppressed remaining warnings in code in spring-test.

Issue: SPR-5613, SPR-9863

Issue: SPR-10128

  find . -type f -name "*.java" -or -name "*.aj" | \
    xargs perl -p -i -e "s/[ \t]*$//g" {} \;

Issue: SPR-10127

This renaming more intuitively expresses the relationship between
subprojects and the JAR artifacts they produce.

Tracking history across these renames is possible, but it requires
use of the --follow flag to `git log`, for example

    $ git log spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history up until the renaming event, where

    $ git log --follow spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history for all changes to the file, before and after the
renaming.

See http://chrisbeams.com/git-diff-across-renamed-directories