Add Emacs Unicode from lockywolf

[lassik]

@lockywolf OK?

[ghost]

I don't think that avoiding the seq library is a good idea. It's very schemy, basically made in the spirit of srfi-1, non-mutative, whereas append is actually append!, and I think it will be destructively appending the list to itself (doubling the length) each time you run scheme-mode. But I'm not very sure, because I avoid using "old lisp" primitives as much as possible.

[lassik]

Since the cookbook is intended to have wide applicability, I switched to append which comes standard with Emacs. append is the same in Emacs Lisp (and Common Lisp) as it is in Scheme: it copies all except the last argument. nconc is the ELisp and CL function to append lists destructively.

[ghost]

Seq also comes with standard Emacs (https://www.gnu.org/software/emacs/manual/html_node/elisp/Sequence-Functions.html), and is, in all respects, a more consistent and compatible.

Excessive compatibility with something that changes as quickly as Emacs, and in a cosmetic domain (which is itself subjective) makes no sense.

You are right with respect to append, and I am wrong, but, again, I see no benefit in using it.

[lassik]

OK. I don't understand your arguments, but let's go with seq-concatenate since it's your solution.