v2.1.2

What's Changed

• switch to spf13/pflag by @tjblackheart in #21
• udate README, move import by @tjblackheart in #22
• Fix double error print by @tjblackheart in #23
• regression: disable flag sorting by @tjblackheart in #24
• Add description, update README by @tjblackheart in #25

Full Changelog: v2.1.1...v2.1.2