reset method
void
reset()
Reset this cell to its default (empty) state.
Implementation
void reset() {
symbol = ' ';
fg = Color.reset;
bg = Color.reset;
fgRgb = null;
bgRgb = null;
fgIndexed = null;
bgIndexed = null;
modifier = Modifier.none;
diffOption = CellDiffOption.none;
}