This RT extension adds a "Merge Users" box to the User Administration
page, which allows you to merge the user you are currently viewing
with another user on your RT instance.

It also adds "MergeInto" and "UnMerge" functions to the RT::User
class, which allow you to programmatically accomplish the same thing
from your code.

It also provides a version of CanonicalizeEmailAddress, which means
that all e-mail sent from secondary users is displayed as coming
from the primary user.
