Capture warnings and present them to developers.

### What needs to get done

Use [`logging.captureWarnings`](https://docs.python.org/3/library/logging.html#logging.captureWarnings) to capture warnings and present them in a developer-friendly manner. This should be done in a way that hides them from the user by default.

### Why it needs to get done

Currently we don't capture warnings, so code that raises warnings that don't get ignored could cause weird output.