Unity provides constants that reflect the maximum value of integer types,
use it for checking the checksum overflow rather than using 65536 directly.
This makes the intent more clear.
The Arduino will block if sent data too quickly after connection.
Add a new coroutine to force waiting for 1s+ and update the UI
accordingly.
Update some comments throughout.
The EEPROM in the cartridges support 'Fast I²C' at 400kHz.
Testing it out, it seems to work fine despite the high pull-ups,
so update the Arduino code to enjoy the 4x speed-up !
