`Application.parse_preliminary_options_and_args` was previously, against
expectations, treating empty lists passed as the `argv` argument the
same way it treated `None`s.
This has been addressed and the correct behavior tested for in a unit
test of the `Application` class.
See issue #518 for details.
By splitting out the logic to retrieve and return the formatting class
for an application, we can test it more easily and increase our test
coverage of this critical logic.
Refs #320
If we handle an exception, or early exit, or really anything, we should
exit non-zero (and we used to). This was a minor oversight.
Closes#209Closes#248
