Add support for style tags for theme styles

[fastpok]

Related to #93

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[fastpok]

I haven't been able to sign the СLA yet. Something is not working.

[tomayac]

Thanks for this! Could you add a demo for this as well? And maybe add it as version 3 in the README (mentioning that it doesn't profit form the load optimization that <link> has)?

[fastpok]

Yes, no problem.

[fastpok]

I'm sorry for the long pause. I added a demo and I managed to sign the CLA.

[tomayac]

LGTM, thank you!

[tomayac]

Released as v0.17.0.