Changes in version 2.0.0 (2020-02-17)                  

1.  Deprecation warning for index.name - it was never used.
2.  80% performance improvement on example data due to faster indexing
    of groups.
3.  Additional tests for malformed data.

                 Changes in version 1.0.1 (2018-07-10)                  

1.  Substantial performance improvements owing to vectorization and
    data.table call optimization.
2.  Automated tests using the testthat package.
3.  Cleanup of package directory and administrative files.