When using cap "square" or "butt" the pathstring d has offset that makes it not accurate

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Basically the path data always makes the path starts somewhere half of the width of the stroke and I understand that works for circle but it wouldn't work for square or butt since it is basically adding offset to the beginning of the stroke and missing it up, so "5" percent looks like "15" percent.

Would propose to remove that. I can make a simple pull request for it if you want.