add font-variant support to Text and TextPath

Good afternoon!

I have added the ability to specify the font-variant for Text and TextPath shapes.  I added tests for the getters and setters, but am unsure if there is a good way of writing ones for ensuring the variant is actually applied.

If this needs any additional work, just let me know.  I would love to see this get pulled in, but pending that, I can always use a dev build.  Thanks for the great library!