Implement initial support for Vince USB-DMX512 interface

Implement support for Tx side of Vince USB-DMX512 interface

The USB-DMX512 interface (http://www.dmx512-online.net/en-article58.html) provides one input and one output of 512 channels and it's based on a FTDI chipset. Thanks to the explanations of the constructor, Vince, I've been able to implement the support for the output at the moment.