- Can specify
  ```
  transform
  {
      origin      (1 2 3);
      rotation    none;
  }
  ```
  instead of the longer form
  ```
  transform
  {
      origin      (1 2 3);
      e1          (1 0 0);
      e3          (0 0 1);
  }
  ```

COMPAT: remove old (pre-1812) Euler and STARCD keywords

- use "angles", remove old compat name "rotation"
  as clutter and possible confusion with "coordinate rotation"

STYLE: remove coordinate rotation move constructors

- an unnecessary holdover from older code.