f/review

[mdavy86]

Summary

Added a citations.bib file for references, and fixed some typos.

The last commit 5d0fa13 added all the html pages manually, apart from real changes to code, different machines sessionInfo() environment will be slightly different, one option is to roll back the last commit for the pull request

## rewriting history...
git reset --hard  d674141

merge it, then @stephens999 can build the html pages for another commit using git or wflow_commit(). I can do a roll it back if required before merging.

I noticed viridis was initially missing from my system used in wright_fisher_model.Rmd. Could have a config somewhere (maybe in chunks.R?) for all contributed package prerequisites;

packages <- c("jviridis")

for(i in packages) {
  if(!require(i, character.only=TRUE)) {
    install.packages(i)
    require(i, character.only=TRUE)
  }
}