hybrid-array: add Deref/DerefMut impls for Array (#908)

Derefs to the inner core array type.

Also adds bounds for `Deref`/`DerefMut` to `ArrayOps`, with a `Target`
of `[T; N]`.

Author: tarcieri

hybrid-array/src/lib.rs

@@ -28,7 +28,7 @@ pub use typenum;
 use core::{
     array::{IntoIter, TryFromSliceError},
     borrow::{Borrow, BorrowMut},
-    ops::{Index, IndexMut, Range},
+    ops::{Deref, DerefMut, Index, IndexMut, Range},
     slice::{Iter, IterMut},
 };
 use typenum::Unsigned;
@@ -151,6 +151,26 @@ where
     }
 }
 
+impl<T, U> Deref for Array<T, U>
+where
+    U: ArraySize,
+{
+    type Target = U::ArrayType<T>;
+
+    fn deref(&self) -> &U::ArrayType<T> {
+        &self.0
+    }
+}
+
+impl<T, U> DerefMut for Array<T, U>
+where
+    U: ArraySize,
+{
+    fn deref_mut(&mut self) -> &mut U::ArrayType<T> {
+        &mut self.0
+    }
+}
+
 impl<T, U, const N: usize> From<[T; N]> for Array<T, U>
 where
     Self: ArrayOps<T, N>,
@@ -273,6 +293,8 @@ pub trait ArrayOps<T, const N: usize>:
     + AsMut<[T; N]>
     + Borrow<[T; N]>
     + BorrowMut<[T; N]>
+    + Deref<Target = [T; N]>
+    + DerefMut
     + From<[T; N]>
     + Index<usize>
     + Index<Range<usize>>