* chore: run codespell on source/header files
Fixes most reported typos discovered by codespell (while trying to be
unopinionated about American vs. British English).
* chore: run codespell on build/readme files
I thought I had tested this on Linux, but I guess I must have only tested cmpsctst.rexx and not this one. Sorry about that! This should hopefully fix things, as long as you have "." (current directory) in your search PATH and set your Hercules "rexx mode" to "subr".