BUGFIX: make sure cosmological priors can be written and read

@jacob.golomb pointed out that cosmological priors can't be written and read in the file format. The code to do this has been present for a long time, but somehow there was a method naming issue that I've resolved here.

changed milestone to %2.1.0

added <10 lines Bug labels

changed milestone to %2.1.1

approved this merge request

approved this merge request

changed milestone to %2.1.2

merged

mentioned in commit 5231e3b5

picked the changes into the branch release/2.1.x with commit 485708b0

mentioned in commit 485708b0