Added arduino-nano to BOARD_INSUFFICIENT_MEMORY/BOARD_BLACKLIST following suit
of how arduino-uno is marked, as arduino-nano is mostly an Uno in a different
form factor.
Add command mode that will be used like this:
mode <dev> <data bits> <parity> <stop bits>
This command must be called after init otherwise
the UART won't be fully initialized.
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
