v2.1.3

Changed various code for parity with KLineKWP1281Lib_ESP32.

Breaking changes:

• the signature of receiveFunction, debugFunction and customErrorFunction has been changed
• debug verbosity is set by KWP1281_DEBUG_LEVEL in KLineKWP1281Lib.h, with 0 removing debugging strings

Be sure to check the example sketches and the Wiki page for more details.