Review notebooks for errors

[jGaboardi]

Following the correction of rendering errors (#16), ensure that notebooks are actually functional.

• 4d_distance.ipynb
• Example_NYCBikes_AllFeatures.ipynb
• NYC_Bike_Example.ipynb
• New_DistanceBand.ipynb
• ODW_example.ipynb
• OD_weights.ipynb
• autograd_test.ipynb
• dispersion_test.ipynb
• glm_speed.ipynb
• local_SI.ipynb
• netW.ipynb
• sparse_categorical.ipynb
• sparse_categorical_bottleneck.ipynb
• sparse_categorical_speed.ipynb
• sparse_grav.ipynb
• sparse_scipy_optim.ipynb
• sparse_vs_dense_grav.ipynb
• test_grav.ipynb
• validate_gravity.ipynb