Message 120833 - Python tracker

Following python-dev discussion on the issue, I would like to propose trace-deprecations.diff patch for review.

I would like to make these changes before turning to issue10342 which will require changing many of these APIs that take a source path to take a module object (or possibly a loader).

Note that CoverageResults presents an interesting case of a class that does not need to be public, but its methods, particularly write_results() need to be documented.