Add more include protection macros to give the user warnings when they try to manually include private driver header files, instead of the public driver headers.

Fixed issue in USBtoSerial demos where the USART Rx line was not having its pullup enabled at startup, leading to noise being received from the Rx pin when left floating.

Removed unused relative Common.h header include from the DriverStubs board stub drivers.

Fixed Benito programmer, use the correct LED functions where needed to ensure correct status display at all times.

All comments in the library, bootloaders, demos and projects have now been spell-checked and spelling mistakes/typos corrected.