Updates to Conditionally Rare Taxa discovery algorithm: v1.1

We're pleased to share updates to the CRT discovery algorithm, published at the ShadeLab GitHub space. CRT version 1.1 includes minor updates. First, a small bug fix in the CRT AbundThresh final filter (Thanks to David Esteban at Vassar College for the catch!), and second, the addition of a new option to calculate CRT with or without including singletons in the dataset. Enjoy, and feel free let us know what you think.