Add decoding to processing module

[celefthe]

Add arbitrary decoding functionality to process module.

This should accept a processed recording file (h5 or nwb), a binary regressor file (npz, generate with visiomode-analysis) and a mask, either as a file (npy/npz), an ABA area or an all option for all ABA areas.

The module should support logistic regression and LDA decoders.

It should output a JSON file with the following keys:

• decoder_type => type of decoder
• decoded_variable => variable decoded
• test_strategy => test strategy used, eg 80:20 split
• train_strategy => training strategy used, eg random_shuffled
• run_date => date decoder was run
• accuracy => accuracy of decoder
• balanced accuracy => balanced accuracy of decoder
• f2_score => decoder F2 score
• confusion matrix => decoder confusion matrix
• d_prime => decoder d'