JostMigenda/sntools: v1.0b1

This is a major new release of sntools with two headlining features: parallelize event generation (#31): On multi-core machines, sntools can now generate events for different channels in parallel. Depending on input parameters, this makes it up to 3.5× faster. SNEWPY integration (#32): Adds support for five additional flavor transformations and six additional input formats for supernova models. Note: At the moment, SNEWPY needs to be installed manually to get access to the neutrino fluxes included in the repository. Additionally, a lot of code was modernized and cleaned up. This leads to some additional performance improvements in --verbose mode and should ensure clearer debug output and error messages when developing or extending sntools. Compatibility notes: This version drops support for all Python versions prior to 3.6 (#29). To add multi-core support, I needed to change how the random number generator is seeded. Therefore, using the --randomseed argument under v1.0 generates a different output file than using the same random seed under v0.7.x. The --ordering (or --hierarchy) argument was deprecated in favor of --transformation. When using the old argument, sntools will automatically translate it to the new argument and print out a warning message explaining how to use the new argument in the future