Reset watchdog when Base starts.
NRF24L01+ interrupt pin is active-low.
Don't forget to init the RH radioManager.
Make base compile: define Sensorino::die, remove RX interrupt.

The UART RX interrupt is already registered by the Arduino UART
libraries, our implementation would conflict.

Sensorino::die is used by Message.cpp but not defined in the
Base since we don't compile Sensorino.cpp into the binary (if the
Sensorino and Base files are split into separate libraries which
is necessary anyway).
Must free the aJson object after done with it.
Message::dataTypeToString now returns NULL on failure.
Fix TLV iterators.

Make sure we skip the length byte in the TLV also.
Fix an inverted equality check.
Enum types as strings instead of ints in JSON.
Fix typo in casting TLV value to proper types.
Better support for "to" and "from" fields in JSON.
Report errors on serial input back to serial.
For now replace RadioHead with a functional mini-library.

Could not get any successful radio communication with RadioHead and it
was taking up a lot of flash and RAM on an atmega, for now replace it
with a mock-up library based on a very simple but tested NRF24 library.