Fixed attribution links for some transcripts

Changelog:

Corrected attribution links for transcripts prepared by anatomyhouse.tumblr.com (formerly prentissed) using a Tumblr-generated permalink, which should hopefully continue to work even in the event of future username changes. (This became an issue because someone else is now at prentissed.tumblr.com – sorry, new-prentissed!)
Where possible, also added hopefully-perma-links for other Tumblr users who have contributed transcripts.

Please email me if you run into any problems.