Actually make \cs, \cmd, etc. work in moving arguments

Now the arguments of \cs, \cmd, etc. are also protected when
they are written to a file (or more generally x-expanded).


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5330 de43f980-851b-0410-b2f7-c40aca1f87e0