Log warnings when using non-existent options

Fixes #343 

This was fun! Some highlights:

  - I discovered a previously-undocumented option, `gridLinePattern`.
  - I removed a few references to non-existent options from auto_tests.
  - I switched auto_tests to use new-style options where they weren't explicitly testing old-style options.
  - I switched all the tests to use new-style options.
  - I discovered that `isPixelChangingOptionList` didn't know about new-style per-axis and per-series options.

I fixed this last item, but this revealed that there were some pixel-changing options which were marked as not being pixel-changing. This is a bit scary!
Please forgive me if I missed this, but why "warn" and not just "throw"?