Changes in version 1.5.3 (2023-03-19)
+ Added paramter to "train_classifier" and "test_classifier" to set the characters
  that identify cells as ambiguous.

Changes in version 1.5.2 (2023-03-05)
+ Automatically include parent classifiers if only a subset of classifires is selected.

Changes in version 1.5.1 (2023-01-17)
+ Added check to ignore any classifiers / cell types for which genes are missing in the dataset.

Changes in version 0.99.2 (2021-23-07)
+ Adapted code based on Bioconductor review
