FIX: Swap rhoB and rhoW to match tables in PEER report and EqSpectra paper.

The rhoB and rhoW columns in AG20.csv were swapped compared to the tables in the PEER report (Table 5.4) and the EqSpectra paper (Electronic supplement Table E6).

Fixes #255 (closed)

I do not know how the test data were generated. I suspect the test data need to be updated in accordance with this fix.

Will resubmit change that includes updated unit test results as well as fix for #256 (closed)

closed