Changes in Version 1.23.1 (2020-04-18)

* ASSIGN no longer changes the working directory
* ASSIGN requires that output files do not exist before functions run

Changes in Version 1.17.2

* Bugfix ComBat.step2 by forcing ComBat input to be a matrix
* Added new argument to assign.wrapper to specify direction of signature genes.
* parameters file in assign.wrapper is now in yaml format.
