Fonts

[gadenbuie]

I used Fira Mono (title) and Fira Sans (cell text) originally, but I think "Fira Sans Condensed" is a better choice for cell text.

I also used sysfonts to grab fonts from Google and showtext to ensure they are handled consistently across systems (in particular where the fonts aren't already installed).

We should probably invest some code or time to make sure that either we have good defaults that will work wherever ggplot2 does or that we have some code in place to make sure that our default fonts are available.