Change caching to precompiled HTML

[banfai]

Fixes #3

[banfai]

weird...
the results of this is different from the current vignette:
https://bedapub.github.io/designit/articles/invivo_study_design.html#cage-arrangement-in-rack and
https://bedapub.github.io/designit/articles/invivo_study_design.html#individual-animals-in-cages
vs the same in https://github.com/bedapub/designit/suites/9096990658/artifacts/421684661

also, most of the examples in
https://bedapub.github.io/designit/articles/plate_scoring_examples.html
but not all of them 🤯

[idavydov]

@banfai could be related to R version random generator?

Should I review?

[banfai]

@banfai could be related to R version random generator?
R 3.6.0 was released in April 2019, I don't think we've compiled the previous vignettes that long ago 😄

Should I review?
I suppose if we're OK with the differences then yes please.

@julianesiebourg @ingitwetrust do you think it's concerning that the old vignettes are different from the new?
(see #8 (comment) )
Could you please also review?
update: something has changed since the last rendering of the children, @ingitwetrust tried and the rerendering with the old caching yields the same results as the new caching (both are different from the old, but identical to each other)

[idavydov]

I think it looks good, thanks!