Draft/outline of spreadsheets (#949)

* Add draft/outline of spreadsheets

* Finish reading from Excel

* Write to Excel + consistency edits

* Add pkgs for writing Excel files

* Release the 🐧s

* Reogranize to highlight tibble/data.frame diffs

* Write again

* Add spreadsheets reference + rename_with janitor

* Move janitor to TO DO in rectangular data

* Need to load tidyverse

* Show csv file

* Add TO DO note

* Use students instead of challenge file in this chp

* Quiet down some of the redundant messages

* Add bit on reading in multiple files

* Fix up students example

* Revert back to old dataset to match spreadsheets chapter

* Fix typos

* Use US spelling

* Comments from Hadley

* Incorporate Hadley's suggestions

Co-authored-by: Hadley Wickham <h.wickham@gmail.com>

DESCRIPTION

@@ -27,7 +27,12 @@ Imports:
     pryr,
     stringr,
     tidyverse,
-    viridis
+    viridis,
+    readxl,
+    writexl,
+    openxlsx,
+    palmerpenguins,
+    janitor
 Suggests:
     bookdown,
     bslib,