Add U576 type alias (#94)

Useful for RustCrypto/elliptic-curves#600 as well as `p521`.

Author: tarcieri

src/uint.rs

@@ -243,6 +243,7 @@ impl_uint_aliases! {
     (U384, 384, "384-bit"),
     (U448, 448, "448-bit"),
     (U512, 512, "512-bit"),
+    (U576, 576, "576-bit"),
     (U768, 768, "768-bit"),
     (U896, 896, "896-bit"),
     (U1024, 1024, "1024-bit"),

src/uint/macros.rs

@@ -6,7 +6,7 @@ macro_rules! impl_uint_aliases {
     ($(($name:ident, $bits:expr, $doc:expr)),+) => {
         $(
             #[doc = $doc]
-            #[doc="unsigned big integer"]
+            #[doc="unsigned big integer."]
             pub type $name = UInt<{nlimbs!($bits)}>;
 
             impl Encoding for $name {