This directory is to be used for documenting changes made relative to official
arc, especially changes to its core functionality, "hacks" that change or add
code in ac.scm, arc.arc, or the other files that come with Arc. Libraries, in
particular, are outside the scope of this project. Why a directory instead of a
single file? Because that way documentation can be maintained and updated
separately for different changes. Each file in this directory, save this README,
should be named after the hack it documents. Documentation is of course
optional, but recommended: it helps someone browsing the source or version
history understand the intent of the changes made, and it helps newcomers with
"feature discovery".