R1:a3d282d33efe

Somewhat improve meme transform code so it is merely very bad

Summary: Depends on D19200. Fixes T5258. Ref T13101. Attempt to simplify and modernize this code and improve error handling.

Test Plan: did real hard dank memes

Maniphest Tasks: T13101, T5258

Differential Revision: https://secure.phabricator.com/D19201