1.9.1
    - Add several parameters to control fast version of MetaNeighbor and MetaNeighborUS
    - Add function to pre-train MetaNeighbor models.
    - Add preprocessing function to merge SingleCellExperiment objects.
    - Add utility functions related to meta-clusters, cluster graphs and visualization.
1.3.0 
    - Added memory efficient version of MetaNeighbor and MetaNeighborUS
    - Added supporting functions for memory efficient versions
1.2.0 No updates!
1.1.0 Updated topHits to evaluate with tied ROC values
