Actually, I just read through the feature request again and see that this is meant to directly mirror something in `Mapper`, so this makes perfect sense. I do think it might be reasonable to be able to do it per record type as well (e.g., if part of the application interacts with a legacy db and another part with a newer one that uses different conventions), but no reason to add that in unless people explicitly ask for it.

If we're going to mirror `columnName`, does it make sense to also pass in the `MongoClient` instance? (In `Mapper.columnName` the connection identifier is passed—this does allow discriminating so that say one db can get a different convention than another one.)