Add loc as extras

[non-descriptive]

https://github.com/cgag/loc
fastest counter of lines of code. crossplatform

[nerosnm]

I would suggest that tokei be added instead - even the author states in the README for loc that tokei should be used instead.

[non-descriptive]

loc's author encourages to try both to compare not use istead.
tokei considered as more accurate. It have more categories, warns on invalid utf sequence inputs and mark according categories as innacurate. And it's really hard to measure how much - differences for the same codebases and same categories differs up to 100k pure lines in both directions. tokei have ~12% larger binary size. It's 50% slower on 10k+ file/2M+ sloc codebase and almost 2 times slower on 30k files/9M+ sloc codebase with almost similar outputs.
As extra feature loc has --include filter aside --exclude.