Add check of completeness of data transmission
Every data line in the raw xml file contains a checksum to check for data completeness. From time to time, some characters are left out and then the line becomes unreadable. At the moment, the whole profile is not treated as soon as 1 sensor does not work. In the Soundnine manual, the procedure is described (R0123_XT_Sensors_V2.pdf). I successfully extracted the checksum from each line and calculated the checksum. I found out using an online calculator ([https://www.scadacore.com/tools/programming-calculators/online-checksum-calculator/]) that the method used is "CRC-16-CCIITT, reverse, little endian. However, I tried 2 different methods to calculate this (one from the Soundnine manual, one found in the internet ([https://stackoverflow.com/questions/25239423/crc-ccitt-16-bit-python-manual-calculation]) but none of them agrees with the checksum in the line. My first attempts are done on the checksum branch.