- more sensible/performant defaults: default to primary repositories
only for the last year rather than all repositories forever
- allow specifying more than one user at a time
- output the breakdown of contributions without needing `--csv`
- add a space before the `--csv` output
- consolidate some code
- avoid counting authored commits twice, to improve performance
- retry failed GitHub API calls (this happens often when querying all
maintainers)
- stop counting after we find 1000 commits for a given user to avoid
excessive API queries/pagination