v0.4.2

Changelog:

Stop blocking the main loop
SCPI_Parser::GetMessage now returns NULL if the message is not completed, but reads the available chars at the interface.
As a consequence, SCPI_Parser::ProcessInput no longer waits until a termination char is received.

Communication errors handling, including:
-Message buffer overflow,
-Timeout before receiving the termination chars (uncompleted messages),
-and receiving an unknown command.
See Error_Handling.ino example

Lower RAM usage by storing commands as hashes.
See CommandTree_Check.ino example

Better documentation.