Converts ENMevaluation objects made with version <=0.3.1 to new ones made with version >=2.0.0.
ENMevaluation_convert(e, envs)
ENMevaluation object: the old object to convert
RasterStack: the original predictor variables used to generate the old ENMevaluation object (these are used to make the new occs and bg slots which contain the predictor variable values)