generally unused, as it is incompatible with the Tcl/Tk build of
magic. However, I had not intended to remove it, only move the
name from "readline-4.3" to "readline". But "readline/readline"
was in .gitignore, which caused the contents to be removed from
the repository. This commit restores those files, and also
prevents the readline directory Makefile from making a symbolic
link called "readline" to itself, which was causing compile-time
issues. The readline code is only kept for backwards compatibility
with ancient versions of magic not using the Tcl/Tk interpreter.
1cec414618