py.test with pep8 (defaults to on) and htmlcov (optional)
PEP8 fixes
pretty much all whitespace/indentation changes of some sort:
- Adding in extra whitespace
- removing trailing whitespace
- where Arve Knudsen used the align form of line continuations switch to the hanging indent form (the align form is not possible when using tabs)
Follow concurrent.futures.Executor.shutdown semantics correctly

An executor should have a shutdown method (not a close method) that blocks until all jobs are complete releases resources
After an executor has been shutdown, it should raise a RuntimeError
Removed extraneous function I added.

This is a vestigial function from a bug I fixed earlier. (after second-guessing Arve before second-guessing [third-guessing?] myself)
Test all executors

The default executor, the QThreadExecutor and the 2 builtin executors (ThreadPool and ProcessPool)
Pass on exceptions caught in thread worker
Actually use the executor