Eliminate parsing chapter (#1128)

Originally the plan was to have two chapters about reading text files, a brief introduction in the whole game, and then a more detailed exploration later in the book. This organisation didn't seem to work very well because the second chapter didn't have much content, so I've removed it, integrating its content elsewhere in the book:

* Column parsing types moved back into data-import
* Specifics of parsing various data types (e.g. `col_number()`, `col_date()`, and `col_factor()`) moved into the corresponding data type chapters.
* String encoding has moved to the strings chapter

While I was in here I also removed the unused `import-other.qmd`; we had planned to survey other options but I no longer think this is worth it.

spreadsheets.qmd

@@ -12,7 +12,7 @@ status("drafting")
 So far you have learned about importing data from plain text files, e.g. `.csv` and `.tsv` files.
 Sometimes you need to analyze data that lives in a spreadsheet.
 In this chapter we will introduce you to tools for working with data in Excel spreadsheets and Google Sheets.
-This will build on much of what you've learned in @sec-data-import and @sec-import-rectangular, but we will also discuss additional considerations and complexities when working with data from spreadsheets.
+This will build on much of what you've learned in @sec-data-import but we will also discuss additional considerations and complexities when working with data from spreadsheets.
 
 If you or your collaborators are using spreadsheets for organizing data, we strongly recommend reading the paper "Data Organization in Spreadsheets" by Karl Broman and Kara Woo: <https://doi.org/10.1080/00031305.2017.1375989>.
 The best practices presented in this paper will save you much headache down the line when you import the data from a spreadsheet into R to analyse and visualise.