Tidy up unused images and dependencies (#1133)

* Remove unused images. Fixes #1132
* Remove unused dependencies

images/embed_jpg.R

@@ -1,28 +0,0 @@
-is_latex <- function() {
-  identical(knitr::opts_knit$get('rmarkdown.pandoc.to'), "latex")
-}
-
-embed_jpg <- function(path, dpi) {
-  dim <- jpg_dim(path)
-
-  if (is_latex()) {
-    width <- round(dim[2] / dpi, 2)
-
-    knitr::asis_output(paste0(
-      "\\includegraphics[",
-      "width=", width, "in",
-      "]{", path, "}"
-    ))
-  } else {
-    knitr::asis_output(paste0(
-      "<img src='", path, "'",
-      " width='", round(dim[2] / (dpi / 96)), "'",
-      " height='", round(dim[1] / (dpi / 96)), "'",
-      " />"
-    ))
-  }
-}
-
-jpg_dim <- function(path) {
-  dim(jpeg::readJPEG(path, native = TRUE))
-}