1.0 releases

This is a tracking ticket for 1.0 releases of all of the crates in this repository, except for signature which is already 1.0 (see RustCrypto/traits#237).

The main blocker for 1.0 releases of crates in this repository has been a desire to stabilize them after Rust ships stable const generics. There is now hope this may happen soon enough to warrant putting together a 1.0 stabilization plan:

https://without.boats/blog/shipping-const-generics/

That said, many of the crates maintained by this org have relatively fancy usages of type-level arithmetic using GenericArray which probably won't be available on stable Rust for a much longer period of time.

My best guess is we'll be trying to ship 1.0 versions some time in 2021. In the meantime, this is a place to track upstream Rust progress and make a plan for both replacing existing usage of GenericArray with const generics as well as shipping 1.0 versions of these crates which use a const generic API.

Start by reviewing the crates in this repository, the linked Rust const-generics article, and the existing GenericArray usage described in the issue. Determine which crates need const-generic API changes and define a stabilization plan for their 1.0 releases. Done means an agreed plan exists; the issue does not identify specific files or tests.