* Move producer configuration into configure(...) method of Python API

* Enable output from OpenPose in Python API by making VectorDatum an opaque STL type

* Return empty arrays as None in Python API

* Add type_caster for Array<long long> for datum.poseIds in Python API

* Add ThreadManagerMode enum to Python interface

* Update Python tutorial in line with updated interface and add demo of AsynchronousOut mode

* Remove static_cast of ThreadManagerMode which is no longer needed

* Only set up producer in Python API when SynchronousIn is set

* Fix up memory handling in emplaceAndPop

* Pass AsynchronousOut in async out example