The rustc backend targeting .NET now works with `cargo`(on Linux)

rustc\_codegen\_clr now works with cargo!

I have recently made some significant improvements to the project, and it now works with cargo! The codegen is enabled on a per-sesion (command prompt window) basis, allowing you to run Rust code in .NET by simply typing cargo run. This new functionality should work on all unix-like operating systems, windows support is planned but not a high priority.

This newest set of patches also brings in a bunch of performance improvements, with 7x speedup during compilation of the standard library (now finishes in \~25s).

The code handling intrinsics was also reworked, simplifying the process, automatically inlining them, and adding more robust support for far more of them.

Currently, the project is almost able to properly build core, with the few remaining issues being dynamic types and harder to implement intrinsics, like saturated arithmetic.

With those newest advancements, I fell more confident releasing the project in a pre-alpha state.

If you are interested in taking a look at the project this early, buggy and not ready for production state, feel free to take a look at the installation/quick-start guide.

Due to how the installation process works (it just changes the RUSTFLAGS temporary environment variable), the project will make no changes to your system and Rust installation. Everything is reverted as soon as you close the terminal (command prompt) window.

Please let me know if you have any questions / feedback. I am especially interested in feedback related to the quick-start guide, since it is the first time I am writing something like this.