Add timeout support to terminate hung tests

[jd0-sag]

Galvan doesn't currently make any attempt to terminate hung or unresponsive tests. This means something else has to terminate them.

Internally, this wouldn't be difficult to implement. Optional settings would allow the framework to directly declare a test as failed due to a hang:

• Maximum test time - terminate the test once this much time has elapsed since the harness started running any test-related code (this would also mean that hangs in "setup" clients would be considered hung failures)
• Maximum inactive time - terminate the test if this much time has elapsed since the last event was processed by the framework's state machine (this would allow a tighter bound on hangs since many tests could be slow but typically interact with the harness fairly frequently)