produce transcript of all changes for stats/undoing

[lsloan]

The application was initially designed to allow a migration to be "reversed" by swapping the source and target tools in the configuration and running it again. However, in some courses, the target tool may already be in the course or its nav bar before the initial migration. The application warns about this state. Running a reverse migration in the way described here would hide those tools that had been the target, which is a Bad Thing™ because they had existed before the initial migration.

The only way to really provide an undo option would be to keep track of the changes made by the application. That is, without friendly messages, etc. A simple transcript of what was added, hidden, or revealed. Then that log could be used, either manually or with some other application, to undo a migration.

The transcript would also be helpful for statistical purposes.