Pre-PEP: Rust for CPython

Introduction We (@emmatyping, @eclips4) propose introducing the Rust programming language to CPython. Rust will initially only be allowed for writing optional extension modules, but eventually will become a required dependency of CPython and allowed to be used throughout the CPython code base (see update here about requiring Rust). Motivation Rust has established itself as a popular, memory-safe systems programming language in use by a large number of projects. Memory safety is a property of a ...