Added StyleSheetId to the schema, solving a bug that kills react.

[michaelthatsit]

I'm working on a project called Malloci, which would be impossible without this component. but when trying to integrate Malloci into a react app, I realized htmlembed was reloading every styllesheet on the page anytime a component was created, resulting in page freeze up, and total loss off page formatting. adding styleSheetId to the component and styleId to the htmlcamvas code tells the component to only reload the CSS relevant to the component. This improves performance and prevents the side effect of format loss.

[lmcarreiro]

This PR seems to be a workaround for #19 and #22, thanks for sharing....

I'll try it here, but do you know if there is a way to handle this without having to provide the style id? It seems the issue doesn't happen because it reloads every stylesheet, as I understood, it issue happens because it does it many times instead of doing it once.