* fix negative temperature (OpenDTU issue 246)
* added plausibility check based on payload length
* prepared project for splitting into library and end-user-esp
* added donation link to index.html
* deactivated disclaimer temporarily
* build CRC over settings, only if the CRC matches settings are applied
* send command 0x80 (set time was wrong)
* improved crc16 routine
* added statistics for received commands and send statistics (channels are not correct for now!)
* receive of commands 0x01, 0x02, 0x03, 0x81 and 0x84 working