charmap does not correctly handle commands with letter names

[rhaas80]

In charmap.pm there are replacements like this:

TeX-Encode/lib/TeX/Encode/charmap.pm

Line 646 in d449a33

chr(0x015f) => "\\cs", # ş

which use a LaTeX command \cs which does not exist (at least for me LaTeX version). Instead to get ş I have to write \c s or \c{s}. Eg:

\documentclass{article}
\begin{document}
\cs
\end{document}

results in

This is pdfTeX, Version 3.14159265-2.6-1.40.21 (TeX Live 2020/Debian) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./foo.tex
LaTeX2e <2020-02-02> patch level 5
L3 programming layer <2020-09-24>
(/usr/share/texlive/texmf-dist/tex/latex/base/article.cls
Document Class: article 2019/12/20 v1.4l Standard LaTeX document class
(/usr/share/texlive/texmf-dist/tex/latex/base/size10.clo))
(/usr/share/texlive/texmf-dist/tex/latex/l3backend/l3backend-pdftex.def)
No file foo.aux.
! Undefined control sequence.
l.7 \cs

?

[a3f]

In charmap.pm there are replacements like this:

Did you identify any other wrong substitutions?

[rhaas80]

Quite a number, I think most of the two-letter ones do not work for me. Exceptions as things like \DH (ETH) or \AA. Some of them I know how to fix (eg anything that starts with \u or \v), some I am not sure how they ended up the way they are (eg. \V for a circumflex below in Ḙ which is seems to require something like \textsubcircum{E} instead and then would only work in text mode, not math mode [if that is a concern]).

I will make a pull request.