Allow dereferencing an Unalign, add trait impls (#126)
Allow dereferencing an Unalign, add trait impls (#126)

Provide methods and trait implementations to generate `&T` and `&mut T`
from `&Unalign<T>` and `&mut Unalign<T>` respectively. If `T:
Unaligned`, then these are infallible. Otherwise, a runtime check must
be performed to ensure that the `Unalign<T>` satisfies `T`'s alignment
requirement.

Since dereferencing is now supported, we can also implement various
traits using `Deref` and `DerefMut` impls.
google/zerocopy,google/zerocopy