Updated SXS Collaboration catalog of binary black hole simulations

To extract the maximum science from gravitational wave detections of merging black holes, it is necessary to have accurate models for expected events. Numerical relativity is the only ab initio method of computing gravitational waveforms for binary black holes near merger. We present a major upgrade of the public Simulating Extreme Spacetimes (SXS) Collaboration catalog of numerical-relativity simulations for binary black hole mergers. The catalog contains significantly more simulations than the previous version, includes more precessing and eccentric simulations, simulations with a larger number of binary orbits, and more extreme spin magnitudes and mass ratios. Many of the older simulations have been deprecated and superseded by new, more accurate ones. Finally, a public python package called "sxs" provides an easy-to-use interface that allows the user to access catalog data from the cloud and manipulate those data as python objects, without worrying about details of data storage and file formats.