Rust changes for v6.2 The first set of changes after the merge, the major ones being: - String and formatting: new types `CString`, `CStr`, `BStr` and `Formatter`; new macros `c_str!`, `b_str!` and `fmt!`. - Errors: the rest of the error codes from `errno-base.h`, as well as some `From` trait implementations for the `Error` type. - Printing: the rest of the `pr_*!` levels and the continuation one `pr_cont!`, as well as a new sample. - `alloc` crate: new constructors `try_with_capacity()` and `try_with_capacity_in()` for `RawVec` and `Vec`. - Procedural macros: new macros `#[vtable]` and `concat_idents!`, as well as better ergonomics for `module!` users. - Asserting: new macros `static_assert!`, `build_error!` and `build_assert!`, as well as a new crate `build_error` to support them. - Vocabulary types: new types `Opaque` and `Either`. - Debugging: new macro `dbg!`.