History of Field::colour 1 change

In crates/backdrop/src/field.rs, lines 129–144 on dc71378db1dc95169f80a85c58c80bc86dbd44546a90607b3a49297ec2e1843e. 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.