Use tokei instead of cloc in editorialbot

[DanNixon]

Currently editorialbot gives a summary of lines of code using cloc, this is helpful, however tokei provides a little more information by showing languages within other files.

This can be a helpful proxy metric of things a reviewer may care about, the two examples I have used in the past:

• the amount of Markdown in Rust source code is an indicator of how extensively the code is documented
• the amount of any programming language in Markdown documents is an indicator of usage examples in the documentation

[guomengtao]

I like this idea! Tokei seems to provide more detailed insights than cloc, especially showing languages inside non-code files.

It could definitely help reviewers get a better sense of documentation and usage examples. Looking forward to seeing this in editorialbot!