Simulations to compare freyr with other pipelines (and to compare parameter settings within freyr)

[jackscanlan]

Following on from email with Alex. Simulations could be useful when validating the pipeline and comparing internally and externally.

See this paper: https://onlinelibrary.wiley.com/doi/abs/10.1111/1755-0998.13430
Simulation code from that paper is here: https://gitlab.mbb.univ-montp2.fr/edna/metabarcoding_data_simulations