Utility for redirecting C++ streams to Python (#1009)

diff --git a/setup.py b/setup.py
index 6e7a40a..e24f34b 100644
--- a/setup.py
+++ b/setup.py
@@ -28,6 +28,7 @@
         'include/pybind11/embed.h',
         'include/pybind11/eval.h',
         'include/pybind11/functional.h',
+        'include/pybind11/iostream.h',
         'include/pybind11/numpy.h',
         'include/pybind11/operators.h',
         'include/pybind11/options.h',