Imports and registers the Calibri font for use in ggplot2 plots when using the themeDarwin.
requireExtrafont(device = "win")
Invisibly returns TRUE on successful registration.
Character string indicating the graphics device to load the fonts into (e.g., "win", "pdf", "postscript"). Defaults to "win" (Windows).
This function is required only once per R installation or after installing a new font. It uses the extrafont package to map system fonts to R's graphics devices.