Changes

Added AVR examples.
Fixed missing byte count in responses. Issue #4.
Added AVR standard vector library support. Issue #2
Added global switch macro for enabling/disabling debug messages.
Fixed array out of bounds error when sending back register data.
Added test sketches.
Implemented dynamic debug message printing functionality. The user can now enable/disable the debug messages on the fly.
Added include guard.
The Vector library ArduinoSTL has issues when used with AVR boards. A fix is available in a PR mike-matera/ArduinoSTL#94. But this has not been merged yet. Users who use the the CSE_ModbusRTU library will need to fix this issue manually.
Updated Changes.md style.

Provide feedback