svg background shouldn't be applyed as style prop

[uf0]

https://github.com/rawgraphs/rawgraphs-core/blob/master/src/raw.js#L142

If we use style prop we lose it when we export to .svg. Background should be a <rect fill="my background color" width="full width" height="full height" x="0" y="0" /> element inside the svg

[mikima]

ok, will add it to all the chars

[bianchimro]

@mikima @uf0 do charts still rely on this?