Remove all deprecated classes and methods.
Review Request #10615 — Created July 2, 2019 and submitted
In Review Board 3.0, we officially marked many classes and methods for
deprecation, stating they'd be removed in Review Board 4.0. This change
completes that deprecation process, completely removing them all from
In many cases, this will trigger import errors in any extensions that
attempt to use these. In a few cases, the breakages will be due to the
wrong methods being implemented by subclasses. Each one, though, would
have resulted in a deprecation warning when run on 3.0.
These will be documented in the release notes.
Unit tests pass.