Climbing Ratings 2.0.0

Backwards-incompatible changes since 1.2.0:

• Use a different request to fetch JSON ascent data from theCrag's API. data_prep_json.R will no longer process JSON ascents captured by the old code.
• Replace the "gap" column in pages.csv with "timestamp". run_estimation.py will no longer process pages.csv files generated by the old code, and callers of the WholeHistoryRating constructor must use timestamps instead of time deltas.
• Replace the "gamma" columns in routes.csv, pages.csv, page_ratings.csv and route_ratings.csv with a natural "rating" column. The estimation and post-estimation scripts will no longer process files generated with the old code.
• Add a "cov" column to page_ratings.csv.

Other changes since 1.2.0:

• Various changes to avoid loss of precision in the Python package, the most significant of which was using natural ratings instead of gamma ratings where possible. These changes noticeably improve the estimates, in particular, it remedies the biased relationship between Bradley-Terry residuals and ratings estimates.
• Support estimating pitches of a multi-pitch route independently of the full route; pitch 2 of a route with ID "1337" will generate a new route with ID "1337P2".
• Improve tests for top-level scripts.