Merge to Master Checklist

[madisonmay]

• Tests
• Documentation (readme.io? inline?)
• Cost functions class interface (like updates and regularization) with default
• Auto-intuit best cost function for highest layer of net (cce = softmax, mse = linear, etc...)
• knn.py
• inspect internal state (look at activation)
• stopping functions class interface (like updates and regularization) with default
• CNN