Add options to doctest examples while they are running
Description
dtopts adds options to doctest examples while they are running. When
using the doctest module it is often convenient to use the ELLIPSIS
option, which allows you to use ... as a wildcard. But you either have
to setup the test runner to use this option, or you must put #doctest:
+ELLIPSIS on every example that uses this feature. dtopt lets you enable
this option globally from within a doctest, by doing:
>>> from dtopt import ELLIPSIS
