Several new features related to reporting of performance results from PySys tests. These include a new performance reporter that produces JSON output, a new BADPERF outcome for assertions that detect inadequate performance, and automatic printing of the performance results on the console at the end of a test run, including mean and standard deviation statistics (if multiple cycles were executed), and comparison with one or more baseline performance .csv/.json files (if provided).

Simpler syntax for the __pysys_XXX__ descriptor fields in pysystest.py files, including an easier way to create parameterized tests, and a more natural syntax for configuring the list of modes.

Improvements to how the assertMessage= parameter is handled by the assertXXX methods when an assertion fails. The test failure outcome reasons now contain both the standard outcome reason and the human-friendly user-defined assertMessage if one is provided. For the benefit of anyone working on the test or triaging test results, it is a good idea to add an outcomeReason that describes at a high level what the assertion is checking (and why), to any assertion where it is not obvious.