Fixes UART Parity and DataBits argument validation. Closes #66

I'm not sold that the overhead of adding deprecation warnings is worth it here.

It's very unlikely that someone decided to play with UART, realize that the documented parameters weren't working, not post anything on the forums, then go looking through source code to see how it works. 

Even if there are one or two people who did that, the new Error as you described below should get them on the write track immediately.