4.6.1: Jinx

I knew when I wrote that 4.6.0 might be the last release of 2016 that it was the best way to guarantee my code had a bug that I would have to fix before 2017 hit.

Deepest apologies for the bug!

In the skins-pseudo partial the new hover classes for black and white opacity levels were declaring color when they should have been declaring background color. This is now fixed. Thanks to @amytych for catching this. Also fixed a minor typo where helvetica was declared before helvetica neue in the sans-serif stack which is inconsistent with the helvetica class. Guessing no one noticed that one though. It's fixed now, thanks to @lachlanjc for noticing.