Python driver from Graupner SUMD protocol.

Based on:

-https://www.deviationtx.com/media/kunena/attachments/98/HoTT-SUMD-Spec-REV01-12062012-pdf.pdf

-https://github.com/Benoit3/Sumd-for-Arduino

Tested with GR-12L Reciever on Windows and Ubuntu 16.04 with USB to serial converter (cp210x type).

There are two versions of the python file 2.7 and 3 which correspond to the tested python version. In 2.7 the bytes have to be handled differently.

TODO: *Implement CRC calculation *Read Byte 2 as number of channels *Incorporate FailSafe