Tidy up unused images and dependencies (#1133)

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

diagrams/rstudio-screenshots/diagnostics.R

@@ -1,9 +0,0 @@
-
-
-x y <- 10
-
-
-
-
-3 == NA
-

diagrams/rstudio-screenshots/rstudio-screenshots.Rproj

@@ -1,16 +0,0 @@
-Version: 1.0
-
-RestoreWorkspace: Default
-SaveWorkspace: Default
-AlwaysSaveHistory: Default
-
-EnableCodeIndexing: Yes
-UseSpacesForTab: Yes
-NumSpacesForTab: 2
-Encoding: UTF-8
-
-RnwWeave: Sweave
-LaTeX: XeLaTeX
-
-AutoAppendNewline: Yes
-StripTrailingWhitespace: Yes

diagrams/sample-rmarkdown.Rmd

@@ -1,30 +0,0 @@
----
-title: "Untitled"
-author: "RStudio"
-date: "August 2, 2016"
-output: html_document
----
-
-```{r setup, include=FALSE}
-knitr::opts_chunk$set(echo = TRUE)
-```
-
-## R Markdown
-
-This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see <http://rmarkdown.rstudio.com>.
-
-When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:
-
-```{r cars}
-summary(cars)
-```
-
-## Including Plots
-
-You can also embed plots, for example:
-
-```{r pressure, echo=FALSE}
-plot(pressure)
-```
-
-Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.