Consistent Environment access in XML bean definition parsing code

Issue: SPR-12248
ComponentScanBeanDefinitionParser supports placeholders for entire base-package specification and for type filter expressions

Issue: SPR-10424
Issue: SPR-10425
Defensively use setRemoveOnCancelPolicy for JDK 6 compatibility

Issue: SPR-12238
Message broker thread pools should be set up in allowCoreThreadTimeOut mode

Issue: SPR-12249
Introduced addScope convenience method on CustomScopeConfigurer (for use in WebSocket configuration)