Updated code sample suggestion for 'To Map, or Not to Map'

- Using an Ordering type class instead of extending Ordered
- 'collection map { ... }' style instead of 'collection.map(...)'
- replaced 'straight' foreach with a version that appears more equivalent to the confusing version
Changing the code sample to print all Roman numeral symbols
Inverting candidate answer 4 as a potentially more plausible solution?
Removing any declaration order output from the candidate answers:

- Doesn't seem like a plausible solution with a SortedSet
Reviving one declaration order candidate
Changing the declaration order to be different from descending order

To ensure the audience doesn't start suspecting tricks in the definition of compare