TODO url_helper needs fixing

[jim-parry]

Helpers/url_helper::url_title has a todo note...
Remove old 'dash' and 'underscore' usage in 3.1+.

[jeffstoner]

This looks to be complete. In looking at the current code, you can't pass the strings 'dash' or 'underscore' to mean '-' or '_'.

[jim-parry]

I think you are right - it looks like an old note from CI3. Thanks :)