Tachyonix: a very fast MPSC async bounded channel

https://github.com/asynchronics/tachyonix

Another week, another fastest rust channel!

More seriously: Tachyonix is an offshot of Asynchronix, an in-progress async compute framework and runtime for (cyberphysical-)system simulation. Even though it was developed for this specific use-case, it turned out to work pretty well overall so I decided to release a version that should be suitable for general use despite a rather minimalist API. In a nutshell:

1. (let's have this one out of the way) It does use unsafe.
2. It does \not\ use spinlocks. None.
3. Code quality and correctness are a very high priority; bear in mind, however, that this is an initial release which hasn't been tested in the wild yet.

The benchmarks are at the end of the repo. I intentionally don't post them here, hoping that people will first read the limitations and safety sections before jumping to conclusions based on the benchmark figures alone. Everything is a trade-off: make sure Tachyonix is the right trade-off for you before you adopt it.