Collaboration tools (rustfmt, clippy)

[ralfbiedert]

After my last PR I noticed you had to clean up a bit. That made me wonder if it makes sense to configure and use clippy and rustfmt:

• Since clippy is probably less controversial I went ahead and addressed all current issues, either by changing code (where I thought clippy made sense), or disabling lints (e.g., where faster bends rules for speed). Some of the more pedantic lints could be discussed, e.g., usage and formatting of number literals (unreadable_literal, unseparated_literal_suffix). https://github.com/ralfbiedert/faster/tree/clippy

• I think rustfmt makes sense as well, but needs more configuration to resonate with the code. I found a few settings that worked for me (e.g., max_width be set rather high not to break up most macros which makes them harder to read). However you should probably take the lead on that one.

Let me know what you think about clippy, in particular unreadable_literal, unseparated_literal_suffix and type_complexity (I prefer the former 2, no opinion on 3rd). I can then create another PR.

[AdamNiederer]

Thanks, I've been meaning to get clippy and rustfmt working with faster. So far, I've just been doing whatever emacs decides to do. I'll try to integrate clippy into the CI once I get some time (apologies for the response latency and low contribution bandwidth; I've been super busy this past month)