Make Bar.width to be Option<f64> #298

Job	Run time
Code Coverage	1m 55s
Clippy	3m 24s
Build Wasm Examples (wasm-yew-minimal)	57s
Build Examples (3d_charts)	33s
Build Examples (basic_charts)	33s
Rustfmt	13s
semver	3m 37s
Build Examples (custom_controls)	33s
Tests (ubuntu-latest)	2m 16s
Tests (windows-latest)	3m 18s
Build Examples (financial_charts)	32s
Tests (macos-latest)	2m 16s
Build Examples (images)	48s
Build Examples (kaleido)	1m 13s
Build Examples (maps)	29s
Build Examples (ndarray)	33s
Build Examples (scientific_charts)	30s
Build Examples (shapes)	34s
Build Examples (subplots)	32s
	24m 46s

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