Variable input species sets

[rvosa]

The current implementation operates on 'monophyletic' groups of organisms. For example, all primates, or all butterflies. In other words, an entire taxonomic group with all its descendants. However, use cases exist where other groups of species are of interest, such as national checklists (e.g. all species in The Netherlands), or groups that are derived in some other way, such as a random subsample of 1M sequences in the database. To accommodate this, an additional way of defining the input (e.g. a list of names) is needed.