Load all functions when loading a libphutil library

Summary: We can't autoload these, so just load them at startup. This means we don't need to write dependencies for them into init__.php, which moves us closer to being able to remove init__.php.

Test Plan: Ran "arc diff", loaded Phabricator.

Reviewers: vrana, btrahan, jungejason

Reviewed By: vrana

CC: aran

Maniphest Tasks: T1103

Differential Revision: https://secure.phabricator.com/D2545