Niche Module
This module performs neighborhood analysis.
These include the following subcommands:
radial : compute radial profiles of each cell-type
proximity : compute average proximity to each cell-type
sample : randomly subsample cells to allow faster clustering
combine : combine single-cell features from multiple organoids
cluster : cluster cells into niches based on proximity
classify : fit niche classifier to subset and apply to all cells
name : assign names to niches