The AbstractDispatcherServletInitializer now provides support for
the registration of filters to be mapped to the DispatcherServlet.
It also sets the asyncSupported flag by default on the
DispatcherServlet and all registered filters.

Issue: SPR-9696

A new @MatrixVariable annotation allows injecting matrix variables
into @RequestMapping methods. The matrix variables may appear in any
path segment and should be wrapped in a URI template for request
mapping purposes to ensure request matching is not affected by the
order or the presence/absence of such variables. The @MatrixVariable
annotation has an optional "pathVar" attribute that can be used to
refer to the URI template where a matrix variable is located.

Previously, ";" (semicolon) delimited content was removed from the
path used for request mapping purposes. To preserve backwards
compatibility that continues to be the case (except for the MVC
namespace and Java config) and may be changed by setting the
"removeSemicolonContent" property of RequestMappingHandlerMapping to
"false". Applications using the  MVC namespace and Java config do not
need to do anything further to extract and use matrix variables.

Issue: SPR-5499, SPR-7818

Rename ExceptionHandlerSupport to ResponseEntityExceptionHandler and
emphasize the contrast to DefaultHandlerExceptionResovler -- i.e.
one returns a ResponseEntity and relies on message converters while
the other returns a ModelAndView and relies on view resolution.

Issue: SPR-9290