gdverse 1.0-2

• When the discvar input for the opgd, rgd, rid, spade functions is NULL,
  it is assumed that all independent variables in the formula need to be discretized.

• Updating the S3 method for plotting various factor detectors to better conform
  to academic publication requirements.

• Using new example data in the vignettes for spade and idsa.

• Adding the esp function to the package.