- Add a bunch of new keywords
- List all `builtins` explicitly
- Sort alphabetically, to make it easier to spot missing builtins
- Remove `add`, not a real builtin
- Move `or` to `keywords`, this is not a `literal`

- The different string variants have different modes of escapes.
  Split `STRING.contains` into their different variants to reflect this.
- Add escape logic for `'''`
- Add escape logic for backslash escaped characters.

Also ensure comments are handled before any other expressions