Steamcheck

- Added a thread count limit to prevent exceptions from happening while running checker
- Added clean exit when stopping script execution mid-way through using `Ctrl+C`

Based on the popularity of [OGCheckr CLI](https://github.com/checker/cli) comes a newly improved and optimized command-line program made specifically for checking the availability of Steam community IDs and groups.

- Massive improvements and simplification from its predecessor
- One command installation
- Same great features without a stubborn configuration file