And add a way to run tests without long tests:

	zope-testrunner --at-level=1

will run tests without those marked as being long.

By default tox continues to run all tests.

Suggested by @d-maurer with the idea to be able to skip long tests that
are unlikely to fail during development:

https://github.com/zopefoundation/ZODB/pull/368#discussion_r946386969