Allow inbound_nodes or _inbound_nodes in Keras, with deprecation notice
Allow inbound_nodes or _inbound_nodes in Keras, with deprecation notice

In Keras 2.1.3, inbound_nodes has been renamed to _inbound_nodes.
Use a hasattr check to choose which property to use, and warn
the user that support for the <2.1.3 behavior may be dropped.

openai/cleverhans,cleverhans-lab/cleverhans,carlini/cleverhans,cleverhans-lab/cleverhans,cleverhans-lab/cleverhans,carlini/cleverhans,cihangxie/cleverhans