Fixed bug which caused a segmentation fault by setting functionCallback to NULL if not provided to Cmd constructor. Converted the end-of-command character from a macro in Config.hpp to a variable in RxBuff, which is provided in the constructor. Modified existing unit tests accordingly and added new unit tests for specifically testing that the end-of-command char works.
Improved Print class by encapsulating all printing calls into functions, and providing a dynamic way of enabling/disabling them, rather than using macros in Config.hpp.