- `xor` keyword is removed, with `^` used in its place.
- For consistency, also replaced unary `~` with unary `^`, as those
changes come from the same proposal.
- `type` keyword is added.
- To keep existing tests working, parsing support for `type` literal is
added too.
- `is` keyword is removed; we'd already added the `impls` keyword to the
list.
- Several other missing keywords added.
Richard Smith
cb16a1ffca