Add fuzz testing to the regression tests

[rrnewton]

We have this capability now. We've used it for debugging. We just need to apply it to regression testing.

The facility is turned on simply by specifying the WaitMode argument to newLogger.

@peter-fogg I propose we sit down and do this together, because the random-interleavings is an essential tool for LVish debugging and I can walk you through it.