Tighten up documentation of key token lists

These are at least partly needed for internal use, but may also be useful
to the programmer. In contrast to the earlier docs, it is worht noting that
all three are defined in all cases, not only when a key is unknown.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4527 de43f980-851b-0410-b2f7-c40aca1f87e0
Improve documentation for keys

Various tweaks to make things clearer to the user.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4528 de43f980-851b-0410-b2f7-c40aca1f87e0
Improve docs for unknown choice keys


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4529 de43f980-851b-0410-b2f7-c40aca1f87e0