update.run command

[ceedubs]

The add.run command is handy. But if you want to replace an existing term, you have to first delete it (which you may not be able to do if it has dependents) or move it. It would be much more convenient to be able to do update.run thing to replace the thing term with the result of the last run.

Alternatively, the add.run command could be updated to prompt "The term already exists. Do you want to replace this term? (Y/n)" if the provided term name already exists.