Add gf32 module

We are attempting to get this crate to v0.1 (ie, API stabilization).

Currently we use a type call `u5` for the 5 bit math, while valid this
is slightly misleading because our `u5` is not basic integer type.
Within the bech32 encoding scheme the 5 bit type is an element of
GF32 (Galois Field).

Add a `gf32` module that defines a type `Fe32` (Field Element). This
type is similar to the current `u5` but includes add/sub/div/mul over
the finite field.

Introduce the `primitives` module to hold the `gf32` module (and other
future primitive types).

As yet do not make use of the `Fe32` type. Doing so is trivial and will
be done later after more primitive types are added.

Author: tcharding

Cargo.toml

@@ -1,13 +1,13 @@
 [package]
 name = "bech32"
 version = "0.9.1"
-authors = ["Clark Moody", "The rust-bitcoin developers"]
+authors = ["Clark Moody", "Andrew Poelstra", "Tobin Harding", "The rust-bitcoin developers"]
 repository = "https://github.com/rust-bitcoin/rust-bech32"
 documentation = "https://docs.rs/bech32/"
-description = "Encodes and decodes the Bech32 format"
+description = "Encodes and decodes the Bech32 format and implements the bech32 and bech32m checksums"
 readme = "README.md"
-keywords = ["base32", "encoding", "bech32"]
-categories = ["encoding"]
+keywords = ["base32", "encoding", "bech32", "bech32m", "bitcoin", "cryptocurrency"]
+categories = ["encoding", "cryptography::cryptocurrencies"]
 license = "MIT"
 edition = "2018"
 
@@ -20,3 +20,6 @@ alloc = []
 version = "0.7.1"
 default-features = false
 optional = true
+
+[target.'cfg(mutate)'.dev-dependencies]
+mutagen = { git = "https://github.com/llogiq/mutagen" }

src/lib.rs

@@ -55,6 +55,7 @@ use core::{fmt, mem};
 use std::borrow::Cow;
 
 mod error;
+pub mod primitives;
 
 #[cfg(feature = "arrayvec")]
 use arrayvec::{ArrayVec, CapacityError};