Only enable cmdcheck target selectively

This only makes sense for l3doc-based .dtx files: it's not unreasonable for
us to have it in the generic script but shouldn't be enabled by default.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5056 de43f980-851b-0410-b2f7-c40aca1f87e0
Typo


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5057 de43f980-851b-0410-b2f7-c40aca1f87e0
Add a version target

Might be useful to some people: intention is to set the release date by hand
when sending to CTAN.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5058 de43f980-851b-0410-b2f7-c40aca1f87e0