Add cargo clippy checks

[morenol]

Fix cargo clippy warnings and add to the CI something that checks for that.

There is a cargo clippy --fix command that can solve some of the warnings, that could be used at the beginning.

The instructions to run cargo clippy are:

rustup component add clippy # to install it
cargo clippy

[VolodymyrOrlov]

@morenol I am going to close this issue since you have covered most basic checks. Let me know if you want to keep it open.

[morenol]

These are the warning that we are ignoring right now in lib.rs

• clippy::needless_range_loop,
• clippy::ptr_arg,
• clippy::type_complexity,
• clippy::too_many_arguments,
• clippy::many_single_char_names

What do you think about them? Maybe we can move that from lib.rs to the specific places where we have those lint errors and while doing that we can fix some of them, so far I have a branch all the places where clippy::needless_range_loop is happening but not sure if we should fix them or just ignore them.

[VolodymyrOrlov]

I think ignoring these warning is fine for now. From my point of view a lot of these problems can be ignored, like many_single_char_names or too_many_arguments since these problems will not lead to ineffective code or runtime crash.
In my opinion, only needless_range_loop and ptr_arg deserve to be fixed.

[morenol]

perfect, then I will fix them. I also fixed some of the places where ptr_arg was appearing, I will create a PR with that