Gain, Recording Mode, Focal Point, etc. have all been assigned a position in the SD card header block.
The variables are read and implemented for recording, and verified. (haven't verified gain yet, but it should work (writes on register 204))
Markdown README contains all details.
Almost error-proofed (Non-option for recording mode/gain simply defaults to normal mode/x1. Mode-specific variables are simply ignored when not in the corresponding mode.)
To do: Should foolproof the case where the user enters focusMin >= focusMax.
To do: Should foolproof the case where the user enters focusMin >= focusMax.