v1.3

Updated release after field-testing.

Fixed camera power measurement circuitry and functions.
Battery voltage level (for low-battery indication) is now pickup up from serial data from the VTR (if present).
Updated quality-of-life operation features (more sensible VTR power saving, more powerful Rec Review mode).
Updated debug outputs to be used as LED indicators on the adaptor's case.
Dropped support for ATmega48.