In #526 I accidentally lost some of my edits trying to selectively
stage lines with typo fixes, while deleting hunks that were only
whitespace changes. In hopes nobody else falls into this trap, I ran
the following command to find all the files to edit, and apply emacs's
delete-trailing-whitespace function to each file.
```sh
find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi'
```
Note: `git add -u` will add only known paths to the stage (index),
even if `tidy.sh` exists in the git work directory.
* restore underscore, update OpenGL dev links
* add tex/lyx versions of archival documentation
* restore underscore, update OpenGL dev links (#223)
* organize development docs TOC / add git file format directives (#222)
* organize developer TOC
* add git file format metadata/directives
* add "skeletor" to core dev doc; refactor text
* add Vectrexia development guide to core dev docs
* sort compilation guide TOC into cores and frontend
