Make Bar.width to be Option<f64> #287

Job	Run time
Clippy	2m 59s
Build Wasm Examples (wasm-yew-minimal)	58s
Code Coverage	1m 55s
Build Examples (3d_charts)	26s
Rustfmt	15s
Build Examples (basic_charts)	26s
semver	1m 15s
Build Examples (custom_controls)	28s
Tests (ubuntu-latest)	1m 51s
Build Examples (financial_charts)	25s
Tests (windows-latest)	4m 0s
Build Examples (images)	39s
Tests (macos-latest)	1m 45s
Build Examples (kaleido)	1m 7s
Build Examples (maps)	24s
Build Examples (ndarray)	28s
Build Examples (scientific_charts)	29s
Build Examples (shapes)	33s
Build Examples (subplots)	24s
	20m 47s

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