Add Header struct #73

Job	Run time
Preflight crate publish (ubuntu-latest, stable)	19s
Unit tests with minimum versions of direct dependencies (windows-latest)	40s
Unit tests with minimum versions of direct dependencies (macos-latest)	26s
Unit tests with minimum versions of direct dependencies (ubuntu-latest)	18s
Clippy	23s
Unit tests (windows-latest, stable)	1m 1s
Unit tests (windows-latest, 1.72.0)	42s
Unit tests (macos-latest, stable)	1m 6s
License / vulnerability audit (advisories)	16s
Unit tests (macos-latest, 1.72.0)	41s
Enforce Rust code format	11s
License / vulnerability audit (bans licenses sources)	18s
Unit tests (ubuntu-latest, stable)	29s
Unit tests (ubuntu-latest, 1.72.0)	25s
Check for unused dependencies	23s
Preflight docs.rs build	13s
	7m 51s

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