3. label mapping in JointBatchGen
This merge request resolves this issue: #167 (closed)
That is, label mapping to 0,1,2,... is now also implemented for the joint batch generator class.
By default label mapping is enabled (whereas before we had it disabled).
In order to implement this, I had to make some changes to the detailed implementation of label mapping in the batch generator class, but the functionality remains the same.
Also, note that the create_database function now saves a list of unique labels to the table, which can be read by the batch generator.