Make CodeSurfer compatible with mdx-deck 2.x

[vlsi]

Note: this is my first yarn/React experience, so the change might be off the track.
However the support for mdx-deck 2.x seems to be not that difficult.

fixes #53

[vlsi]

PS I have no idea why react-docs fails to build:

$ yarn build
yarn run v1.12.3
$ docz build
{ parser: "babylon" } is deprecated; we now treat it as { parser: "babel" }.
▶  start     Creating an optimized production build...
✖  fatal     Failed to compile.

./.docz/app/root.jsx
Module not found: Can't resolve 'null' in '..../code-surfer/fixtures/react-docs/.docz/app'

[vlsi]

website failure seems to be the same as jxnblk/mdx-deck#284 (gatsby still depends on mdx v1 which does not play well with mdx-deck 2)

[AndersDJohnson]

For what it's worth, this worked for me. @pomber any plans to merge and publish support for this?

[vlsi]

Just in case: beware that mdx-deck has lots of pitfalls for delivering slides on stage.
It looks good when you start, however, there are small bits that appear out of thin air (e.g. lack of 16x9, lack of positioning, wrong "next slide" in speaker view, etc, etc), and it is especially painful in case you prepare the slides "a week before the event".

[aleclarson]

The mdx-deck package actually exports all of the components in @mdx-deck/components. See here.