Adds a lints section to the top of lib.rs with the following:
#![warn(
clippy::unwrap_used,
missing_docs,
rust_2018_idioms,
unused_lifetimes,
unused_qualifications
)]
`warn` is used instead of `deny` to prevent the lints from firing during
local development, however we already configure `-D warnings` in CI so
if any lint fails on checked-in code, it will cause a CI failure.
This commit also fixes or explicitly allows any current violations of
these lints. The main ones were:
- `clippy::unwrap_used`: replaces usages of `unwrap` with `expect`
- `rust_2018_idioms`: no implicit lifetimes, which were present on
usages of `core::fmt::Formatter`
There is occasionally [a need](https://github.com/dalek-cryptography/curve25519-dalek/pull/519#issuecomment-1637770888) to multiply a non-prime-order Montgomery point by an integer. There's currently no way to do this, since our only methods are multiplication by `Scalar` (doesn't make sense in the non-prime-order case), and `MontgomeryPoint::mul_base_clamped` clamps the integer before multiplying.
This defines `MontgomeryPoint::mul_bits_be`, which takes a big-endian representation of an integer and multiplies the point by that integer. Its usage is not recommended by default, but it is also not so unsafe as to be gated behind a `hazmat` feature.
