Grouping Chisel API (#1073)

* Added group chisel API

* Removed println

* Added scaladoc

* Added more tests

* Cleaned spacing and removed println

Co-authored-by: Chick Markley <chick@qrhino.com>
Co-authored-by: Jim Lawson <ucbjrl@berkeley.edu>
Co-authored-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>