[cwconfig] Trim down allowed exceptions in gettext language setting I can't see any valid reason to pass on ImportError and AttributeError. In particular, the latter shadowed a Python 3 error until 4f43e64603ef.

[pkg] Configure "universal" wheel build According to https://packaging.python.org/distributing/#wheels, we should create universal wheels (no 2to3 step, no C extension). Configure this in setup.cfg. [ci skip]