MessageHandlingMember API adjustments

[smcvb]

The MessageHandlingMember currently has it's annotation specific methods deprecated. This is done because the interface should not be reflection specific at all, but allow for different approaches of receiving handler specific information.
Yes, the current implementation is based on annotations, but future implementation would likely use a different approach.

The Handler Enhancers page defines in text and code that the annotationAttributes(Class<? extend Annotation>) method should be used. Instead of this solution, the new approach as defined in this pull request should be picked.