Admin updates fail when changing admin loginname exceeds 25 characters

[jrblakely]

It looks like administrator loginname values may be up to 66 characters in phplist_admin table. But the modifiedby column only allows 25 characters, so attempts to change administrator settings fail when the logged in administrator's login name is longer than 25 characters.

For what it is worth, we have adopted the convention of using email address as the loginname, and many of our user email addresses are longer than that.

Suggestion: rather than storing loginname, storing id int could eliminate the need to coordinate table changes.