* `RawTable` has a new type parameter, `A: Alloc + Clone`
* When the `nightly` flag is passed, `Alloc` will be the trait in
`alloc::Alloc`.
* On stable, a minimal shim implementation is provided, along with an
implementation for the global allocator.
* No public APIs changed.
* For `HashMap`, everything is monomorphized to the global allocator,
and there should be no performance or size overhead.

* Change order of type parameters
* Handle null case for `alloc`
* Run rustfmt

Rename `alloc` to `allocation` and `allocator` to `alloc` in
`RawIntoIter`