Move IQ files around, and add decode.

Summary: These are both still really hacky, but committing just to have them in-repo.

Test Plan: Compiled them out-of-repo and tested a lot of times.

Reviewers: jcarter

Reviewed By: jcarter

Maniphest Tasks: T53

Differential Revision: https://phabricator.edgesysdesign.com/D89