Add a script to test keras functional models
Add a script to test keras functional models

We have a C++ script to test functional models using lwtnn, this adds
a short script to test the same model in Keras. At the moment it only
tests a dummy "ramp" pattern, i.e. np.linspace(-1, 1, n_features).

lwtnn/lwtnn,lwtnn/lwtnn,lwtnn/lwtnn