Zero unsafe usage

[littledivy]

Eliminate unsafe code and examine dependencies that use it.

This should have never happened https://github.com/denoland/fastwebsockets/issues/42, my lazy oversight that gone unnoticed in Deno due to single thread usage but impacted other crate users.

[littledivy]

https://github.com/denoland/fastwebsockets/blob/70a4a98c3927b400d5db002441788799c9e58846/src/mask.rs#L107

[countradooku]

why is htis ocmpleted when the unsafe is still used there?

[littledivy]

afaik there is no safe alternative to it without making it slower