Add transfer learning

[marnixteunissen]

To include data from new projects, some ways of doing this:

• transfer learning, retraining last couple of layers with new data
• retraining the complete model with old + new data (inefficient and complicated on-board)
• ensembling, trian new model on new data and combine with original model

[marnixteunissen]

https://machinelearningmastery.com/update-neural-network-models-with-more-data/