2.99.5 (unstable): * Functors (mem_functor, ptr_functor) no longer need to derive from a common functor_base base class, and functors no longer need to have a result_type typedef or alias. * emitters and accumulators no longer need t ohave a result_type typedef or alias. * Remove now-unnecessary adaptor_type type aliases. * Remove some more unused and unnecessary public type aliases.