Add support for swapping and renaming constructors

[tlringer]

Add support for swapping and renaming constructors, including:

• Searching for those equivalences
• Asking for clarification when there are many possible equivalences
• Lifting across those equivalences
• Making it possible to provide just one direction of an for any ornament

[tlringer]

Add a warning that if promote/forget changes, lifting cache isn't cleared; add a way to clear the lifting cache; tell user to do that