Schema (see README): file, well, sample_id, patient_id, timepoint,
is_control, panel, fmo_for, control_group. Only file is required.
Details
fmo_for names the markers a file is the fluorescence-minus-one control for,
comma separated; control_group confines a control to the samples sharing its
value. Both are optional and inert when absent. See parse_fmo_map().
A supplied map that does not cover every input file is a FATAL error: guessing
well->patient assignment from plate order would silently mislabel patients.
