Replace foofactors and fbind with regexcite and str_split_one() (#742)

* Replace foofactors and fbind with regexcite and str_split_one()

* Make the configured Git user available in regexcite

* Fix function-o

Closes jennybc/regexcite#1

* Reinstate `crayon.enabled = TRUE` and the explicit downlit divs

* These chunk envvars have no effect

* Rework how I manage code / files

This meets various requirements I have:
* The code is readily seen and edited in Whole-game.Rmd.
* The code is syntax highlighted in the rendered product, when it should be, and is not, when it should not be.
* Relevant chunks have the copy button in the rendered product.

* Do a couple TODOs

* Use suggestion from @gadenbuie

* Back to previous approach for README.Rmd

I'm having a problem where it doesn't fully display in the chapter AND creates a whole new chapter in the book.

* This was leftover from an experiment

* Back to @gadenbuie's suggestion, but with more backticks

* Improve the test() output

.github/workflows/bookdown.yaml

@@ -37,8 +37,8 @@ jobs:
 
       - name: Configure Git user
         run: |
-          git config --local user.name "$GITHUB_ACTOR"
-          git config --local user.email "[email protected]"
+          git config --global user.name "$GITHUB_ACTOR"
+          git config --global user.email "[email protected]"
 
       - name: Build site
         run: Rscript -e 'bookdown::render_book("index.Rmd", quiet = TRUE)'