!per #3618 Cleanup duplication of life cycle hooks in Processor

 - introduce around life cycle hooks for symmetry with aroundReceive
 - no custom processor-specific life cycle hooks needed any more
 - preStart and preRestart can be overridden with empty implementation
    (interceptors ensure that super.preXxx calls are still executed)
 - all around life cycle hooks can be final
 - standard life cycle hooks are non-final to preserve composability with existing traits (FSM, ...)
Merge pull request #1742 from eligosource/wip-3618-cleanup-lifecycle-hooks-krasserm

!per #3618 Cleanup duplication of life cycle hooks in Processor