* Make distinction between DisplayName and Username in email templates
Store the actual username in the variable named Username and store the
separate DisplayName in another variable. This allows us to access the
actual username when we need, which currently fails if a user has set a
full name.
Fixes#6161
An error occurred
* Use u.Name directly
No need for extra function, also change use in all mail sending
functions here
* Don't include Username when not used
mrsdizzie