Use `Hash` instead of `IterBytes`
`HashMap` has moved to `collections` instead of `std`
Removes unnecessary comments from keycode/scancode code generators.

(There was a commented out type alias which was used in the `IterBytes` implementation.
This is no longer necessary.)
Merge pull request #46 from drbawb/exp/fix-hashmaps-for-master

Exp/fix hashmaps for master