v0.6.0

• Fix skipping first piece of evidence when tagcounting.
• Add test for tagcount.
• Output full sorted transcript table from tagcount rather than only the observed transcripts.
• Add --sparse option to output tagcount matrices in MatrixMarket format.
• Allow cb_histogram subcommand to take gzipped files.
• Allow cb_filter subcommand to take gzipped files.
• Add support for triple-cellular barcodes.
• Add example for Illumina SureCell (https://www.illumina.com/products/by-type/sequencing-kits/library-prep-kits/surecell-wta-ddseq.html)