Adds odd and even parity bit support to Soft::UAT and Soft::UART 

This PR adds (partial) support for odd/even parity bit to Soft::UAT and Soft::UART.
Soft::UAT is able to output the correct parity bit.
Soft::UART does not do checking for correct parity bit yet.
This is implicit 8 bit only. The original code also seems to assume this. A possible rewrite is to initiate data with the stop bits and parity (if needed) and then "or" in the data before adding the start bit.