Input format name: 'rsem' for RSEM gene-level read counts
(*_rsem.genes.results), or 'counts' for generic 2-column gene IDs and
their read counts (e.g. TCGA level 2 RNA expression).
Normal samples (same format as `gene_counts`) to be used as a control to
when normalizing and re-centering gene read depth ratios. All filenames
following this option will be used.