This is possible now that we no longer support go1.12 and brings rclone into line with standard practices in the Go world. This also removes errors.New and errors.Errorf from lib/errors and prefers the stdlib errors package over lib/errors.
Add bolt-based key-value database support. Quick API description: https://github.com/rclone/rclone/pull/5587#issuecomment-942174768