New flag and dependency updates

What's Changed

• updated ArgumentParser to 1.2.2 @henrik-dmg in #9
• made use of @main annotation @henrik-dmg in #9
• Feature #8: Add --exclude-comments|-e flag by @juraj-blahunka in #10

Full Changelog: 0.0.2...0.1.0

SPM Support

The year is 2020 so SwiftGenStrings is now an SPM package and therefore installable via Mint directly. We were also able to greatly simplify argument parsing by using Apple's own ArgumentParser package.
Other than that, errors are now printed in red so you can spot them more easily

0.0.1

Exclude `.DS_Store` files via `.gitignore`