refactoring workflow

[garfieldnate]

What I envision from a typical Java IDE experience:

1. User requests a refactoring
2. IDE presents list of files that will be updated, allows user to confirm. Just the number of files is also fine.
3. User can view a preview of the changes to be made.
4. Some analysis is done to alert the user to potential issues with the changes. For example, perhaps the refactoring of Soar code may be uncertain where a ^<variable>.attribute.name is used, or maybe something went wrong and generated syntactically incorrect code. The user should be able to review these issues before accepting the final changes.
5. The change should be undoable. We don't currently have any project-level undo stack, so this will be some work.

See also #59, #60.