Ok, i scanned the original dolphin package for gmail... Only results from authors.
Also i didnt found any templates.php inside there.
The plugins which you listed are original one which you got from the package.
So, maybe the hackr came through another hole on the server to it. As i remember, Dolphin was checked and branded as hack safe....
I think, that he maybe used a wrong mod or somethingelse. Do you know which kind of mods he installed on the server?