History of Field::colour 1 change

In crates/backdrop/src/field.rs, lines 129–144 on 3d086bc3d69bce9d301a29144eda53851f72a366fe3693b7fc7a418bd1f95137. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 129,144:crates/backdrop/src/field.rs.