Generate a ucsc genome browser file for each metacell cluster

Usage

export_atac_clust_ucsc(
  atac_mc,
  track_prefix,
  output_dir = getwd(),
  clust_vec = NULL,
  normalization = "none"
)

atac_mc: McPeaks object
track_prefix: prefix for generated misha tracks.
output_dir: (optional) name of the directory to write files to
clust_vec: (optional) a vector of length #metacells representing an annotation/clustering (can be output of gen_atac_mc_clust)
normalization: (optional) normalization method, either 'none', 'lfcom' (log2 fold-change over median), 'zs' (Z-scores)