This concerns only the comments for big integer multiplication where the formulas for the coefficients w0..w4 are explicitly listed. These were not completely correct.

Fixed incorrect formulas for coefficients.

Since our MSRV is 1.60, and `alloc` was stabilized way back in 1.36, we
don't need to be conditional about using it anymore. There are still a
few places where we use `std` functionality, like `std::error::Error`,
so that feature flag is still useful, but less than it used to be.

Commit to `alloc` as much as possible

Add feature cfgs for docs.rs

The intrinsic x86/x86_64 versions are still faster though.

The inverse for `MontyReducer` doesn't need a wider type at all!

Avoid some widening operations

style: use strip_prefix instead of manual starts_with/slice

Fixes for target x32

Release 0.4.6