Preserve notation conventions when simplifying.

[lgarron]

Right now, simplification also performs notation normalization in some cases. For example, Rw on 3×3×3 is simplified to r.

I think it would be good to:

• Preserve Rw by default in this case.
• Change the API to perform any of the following ergonomically (in a way that makes it obvious that these options are available and when is appropriate to use them):
  • Simplification without notatioun convention normalization.
  • Notation convention normalization without simplification (with a target convention).
  • Both.