Code review comment for lp:~jml/testtools/deferred-support

Now working in substance, but still a lot of things to do before it can actually be used in anger.

testtools/_spinner.py:219:
  XXX: Not tested. Not sure that the cost of testing this reliably
  outweighs the benefits.

testtools/_spinner.py:222:
  XXX: Also, we probably need to restore the threadpool the second
  time we run.

testtools/_spinner.py:280:
  XXX: It might be a better idea to either install custom signal
  handlers or to override the methods that are Twisted's signal
  handlers.

testtools/deferredruntest.py:28:
  TODO: Need a helper to replace Trial's assertFailure.

testtools/deferredruntest.py:30:
  TODO: Need a conversion guide for flushLoggedErrors

testtools/deferredruntest.py:59:
  TODO: 0.005s is probably too small a timeout for a default.

testtools/deferredruntest.py:60:
  TODO: docstring

testtools/deferredruntest.py:138:
  XXX: Right now, TimeoutErrors are re-raised, causing the test
  runner to crash. We probably just want to record them like test
  errors.

testtools/deferredruntest.py:149:
  TODO: Actually, rather than raising this with a special error,
  we could add a traceback for each unhandled Deferred, or
  something like that. Would be way more helpful than just a list
  of the reprs of the failures.