BLD : adjust min six version to 1.3

[tacaswell]

No description provided.

[mdboom]

Thanks -- I just went with what I knew worked -- I take it you've experimentally determined that 1.3 is sufficient?

There is also an import-time checkout lib/matplotlib/__init__.py that needs to be adjusted.

[tacaswell]

Yes, that is what I using locally (due to some strange ordering in the virtualenv imports) and is the version that ships with current ubuntu.

Fixed and squashed.

[tacaswell]

both 2.x tests are timing failures, not worth restarting.

[fariza]

Seems reasonable to think that "recent" installations will have 1.3.
Worth mentioning that I don't know the details of 1.6 vs 1.3 in terms of functionality....