mergeSparseAll takes in a list of DGEs, with genes as
rows and cells as columns, and merges them into a single DGE. Also adds
libraryNames to colnames from each DGE if expected to be overlap
(common with 10X barcodes). Values in rawData or normData
slot of a ligerDataset object can be processed with this.
For a list of dense matrices, usually the values in scaleData slot of
a ligerDataset object, please use mergeDenseAll which
works in the same way.