New Variable for Username in Email Templates

Working with email templates and there are already a lot of great variables that can be used. However, for my specific use case I found myself wanting to insert the username into the subject line of my email field. The way my store/users are setup the semantics of it just make the most sense.

Unfortunately, after checking with support and the documentation, there currently isn't a user_name variable available. I think this might be a relatively easy add and give us store manager a slightly more versatile tool set!