Username validity checker
Added new featue! Username validity checker! Enter a username into the function and it checks whether:
- Username is taken or not
- Username is valid or not
- That's it...
Docs: https://github.com/Quantum-Codes/ScraGet/wiki/User-API#for-user_extrascheck_userme
Full Changelog: v0.2.0...v0.2.2