We use six sub-modules that aren't available in old versions. Not specifying
this requirement in the setup will lead to much less readable runtime errors.
It's particuarlly problematic for Mac OSX users because the system comes with
an old six version 1.4.1 by default.
[skip ci]
Also made the Travis build ensure that no warnings
are present.
These builds were previously spewing many warnings,
which was hiding warnings for important things like
accidentally using C++11-only features.
Change-Id: I56caeee9db48bc78756a3e8d7c14874630627037
1, objcect_pair_hook is not supported in python2.6, so duplicated key check is removed in 2.6
2, total_seconds is not suppoted in python2.6, changed to compute seconds directly
Fixes the ScalarMapContainer/MessageMapContainer implementations on
Python 3.4, by dynamically allocating their PyTypeObjects using
PyType_FromSpecWithBases, instead of statically allocating them. This is
necessary because Python 3.4+ disallows statically allocating a class
with a dynamically allocated parent.
Signed-off-by: Dan O'Reilly <oreilldf@gmail.com>