Aitk.networks

Major changes:

* Network.predict_from() working on all tested layer types
* Renamed take_picture to display
* Removed set_weights(flat) flag
* PCA now in title of network when Network.predict_pca()

Major changes:

* work on representations for single and multi-input bank networks

Major changes:

* keep aspect ratio of PCA charts
* added sizes for PCA scatter points
* allow PCA on 1-unit layers
* PlotCallback is now UpdateCallback

Major changes:

* Added Network.predict_pca(inputs, colors=colors, set_pca_spaces=True)
* Added Network.fit(save=N) - saves weights every N epochs
* Network.take_picture() now displays as side-effect rather than return value
* Removed Network.display_picture()
* All display methods have a clear=True argument

Major changes:

* Added Network.get_weights(flat=True), Network.set_weights(flat=True)

Major changes:

* fixed bug in tolerance_accuracy