this becomes more relevant now, since the actual MutationMessage iterators
are implemented in terms of a shared_ptr to IterSource. Thus, when building
processing pipelines, we most definitively want to move that smart-ptr into
the destination, since this avoids touching the shared count and thus avoids
generating unnecessary memory barriers.
This means we have rather tight compiler requirements now.
Beyond that, we expect no serious impact; the most notable
C++14 feature we're likely to use soon is type inference
on lambda arguments.
note down some results found out during the C++11 transition.
There is now a clear distinction between automatic type conversion
and the ability to construct a new instance
